Rare-earth ions in solids are a promising platform for quantum technologies because they combine atom-like optical and spin transitions with the practical advantages of a solid-state host compatible with optical and microwave resonators. This thesis studies cavity-coupled 171Yb3+ ensembles in oxide crystals as a platform for collective cavity-QED and many-body physics, motivated by the goal of using rare-earth ions as hybrid quantum interconnects for quantum computation and networking. The central theme is that coupling many rare-earth ions to a shared resonator mode creates a rich setting for studying fundamental collective and many-body physics, while also providing a practical route to microwave-to-optical conversion, protected spin storage, and interfaces between superconducting circuits and optical photons.
\r\n\r\nIn 171Yb3+:YVO4, a nanophotonic cavity coupled to an inhomogeneously broadened ion ensemble reveals collective cavity QED in a solid. This work led to the discovery of collectively induced transparency, a cavity-QED phenomenon arising from collective interference in a driven, disordered ensemble. The same system exhibits optical superradiance and subradiance, and supports an interacting microwave spin system in which dipolar exchange competes with disorder, allowing studies of quantum thermalization. With Floquet control, these spin dynamics can be modified to reveal discrete time-crystal signatures. In 171Yb3+:CaWO4, related experiments demonstrate microwave superradiance, one-axis twisting, and many-body gap protection in a solid-state spin ensemble.
\r\n\r\nThese physics results are developed alongside quantum-technology applications. The 171Yb3+:YVO4 platform further enables low-noise microwave-to-optical transduction with percent-level on-chip efficiency and added noise near the single-photon level, establishing rare-earth ensembles as a promising approach to optical interconnects for superconducting quantum systems. In 171Yb3+:CaWO4, cavity-mediated gap protection extends Ramsey coherence and supports the development of a spin-based microwave quantum memory, including a classical-regime demonstration of storage and optical readout. The final part develops the superconducting qubit architecture needed to drive a rare-earth transducer with single microwave excitations, including qubit readout, tunable-coupler SWAP control, and cable-mode characterization. Together, these results establish cavity-coupled rare-earth ensembles as a versatile platform for studying fundamental cavity QED and many-body physics and for developing quantum technologies.
", "doi": "10.7907/4zys-mm04", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18663", "collection": "thesis", "collection_id": "18663", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05282026-141341552", "type": "thesis", "title": "Emerging Directions in Active and Multi-Layer Meta-Optics", "author": [ { "family_name": "Gu", "given_name": "Yiran", "orcid": "0009-0001-0283-504X", "clpid": "Gu-Yiran" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391x", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Scherer", "given_name": "Axel", "orcid": "0000-0002-2160-9064", "clpid": "Scherer-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Meta-optics, composed of artificial nanostructures that enable precise control of light, have been widely studied for both fundamental science and technological applications. Compared to conventional bulky optical elements, they offer reduced size, weight, and power consumption, along with enhanced and multifunctional capabilities. As the field enters the transition from fundamental scientific exploration to scalable, real-world technologies, this thesis investigates emerging directions in meta-optics by integrating material and fabrication innovations, dispersion engineering, and inverse design to realize high-performance, scalable optical devices while overcoming key limitations of conventional metasurfaces. Active functionalities are demonstrated using silicon\u2013organic slot metasurfaces, where enhanced light\u2013matter interaction enables low-voltage electro-optic modulation, offering a pathway toward high-speed, CMOS-compatible free-space spatial light modulating devices. A central contribution lies in dispersion-engineered resonances, where concepts such as quasi-bound states in the continuum and band/zone folding are leveraged to achieve spectrally selective, and angle- or polarization-insensitive responses. In parallel, a novel fabrication platform for multilayer, high-index-contrast dielectric meta-optics in the visible regime is developed, enabling precise layer alignment and low-loss operation for volumetric photonic structures. Furthermore, a fabrication-robust inverse design framework is developed to realize compact and 3D photonic interconnects, addressing practical constraints in integrated systems. The advances are further connected to system-level applications through the demonstration of a dielectric metasurface-based coronagraph for space imaging. Together, this work establishes a unified framework for meta-optics that bridges fundamental physics, computational design, and advanced material and fabrication platforms, enabling scalable, multifunctional photonic systems for real-world applications.", "doi": "10.7907/6h0q-5t06", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:17732", "collection": "thesis", "collection_id": "17732", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10262025-132142523", "type": "thesis", "title": "Engineering Quantum Resources for Quantum Networking Using Single Rare-Earth Ions Inside Crystals", "author": [ { "family_name": "Wu", "given_name": "Chun-Ju", "orcid": "0009-0007-0882-4812", "clpid": "Wu-Chun-Ju" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Endres", "given_name": "Manuel A.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Alicea", "given_name": "Jason F.", "orcid": "0000-0001-9979-3423", "clpid": "Alicea-J" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Quantum networks are foundational components of quantum technology, enabling transformative applications in secure communication, distributed quantum computation, and enhanced sensing. Rare-earth ions in solid-state hosts represent a leading platform for building such networks due to their exceptional optical and spin coherence properties. This thesis details the experimental realization of a quantum network node using single \u00b9\u2077\u00b9Yb\u00b3\u207a ions in YVO\u2084 coupled to nanophotonic crystal cavities. We demonstrate the fundamental building blocks of quantum networks and develop multiple advanced capabilities, including multiplexing, protected nuclear spin storage, and high-dimensional qudit control, to expand the platform's power and versatility.
\r\n\r\nUsing this platform, we demonstrate heralded remote entanglement between two physically separate devices. A key innovation is a novel entanglement distribution protocol that employs real-time feedforward to cancel spectral diffusion on timescales slower than a single experiment by rephasing the optical transition based on photon arrival time. We also apply real-time phase compensations to entangle \u00b9\u2077\u00b9Yb ions with different optical frequencies. By combining this novel protocol with multiple spectrally distinguishable ions, we demonstrate heralding of a three-ion W state and implement multiplexed remote entanglement. This multiplexing approach increases the entanglement rate by nearly a factor of two, showcasing a scalable pathway to mitigate network overhead.
\r\n\r\nBeyond establishing remote entanglement, we explore the local nuclear spin environment of \u00b9\u2077\u00b9Yb as an integrated quantum resource. We harness the four symmetrically located \u2075\u00b9V nuclear spins to generate multi-qubit Greenberger\u2013Horne\u2013Zeilinger states. Critically, we identify and experimentally verify a decoherence-protected subspace within these states that exhibits insensitivity to common-mode magnetic field noise. By developing a sequence to transfer quantum information into this protected subspace, we establish the \u2075\u00b9VV nuclear ensemble as an integrated, noise-resilient quantum memory.
\r\n\r\nTo further expand the platform's capabilities, we demonstrate coherent control over the four-level ground state of the \u00b9\u2077\u00b9Yb ion, operating it as a qudit. Through development of a new device architecture that enables microwave driving of all transitions and comprehensive characterization of their coherence properties, this work establishes the foundation for higher-dimensional quantum communication protocols that offer significant advantages in network capacity and efficiency.
\r\n\r\nCollectively, these results establish the \u00b9\u2077\u00b9Yb:YVO\u2084 system as a uniquely versatile platform and demonstrate the feasibility of building scalable quantum networks using single rare-earth ions in crystals.
", "doi": "10.7907/kgjp-xe35", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:17056", "collection": "thesis", "collection_id": "17056", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03122025-171512282", "primary_object_url": { "basename": "Caltech_Thesis_TianXie.pdf", "content": "final", "filesize": 39023176, "license": "other", "mime_type": "application/pdf", "url": "/17056/2/Caltech_Thesis_TianXie.pdf", "version": "v7.0.0" }, "type": "thesis", "title": "Scalable On-Chip Platforms for Quantum Microwave-Optical Interface with Solid-State Ensembles", "author": [ { "family_name": "Xie", "given_name": "Tian", "orcid": "0000-0001-6154-1802", "clpid": "Xie-Tian" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Schwab", "given_name": "Keith C.", "orcid": "0000-0001-8216-4815", "clpid": "Schwab-K-C" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Superconducting quantum circuits based on Josephson junctions are one of the most promising platforms for future quantum information processing. Tens of superconducting quantum bits have been integrated on a single chip with performances exceeding the most advanced classical computers. However, these new quantum machines operate at microwave frequencies, which have enormous thermal noise and photon loss at room temperature. This fundamentally limits the future application of this technology in distributed quantum computing and quantum networks. Conversely, optical photons are an ideal information carrier as the photon loss is extremely small in fibers and the thermal noise is negligible at room temperature. Therefore, a quantum transducer that converts between microwave and optical frequencies at the single-photon level is of great importance.
\r\n\r\nThis thesis is centered on building such chip-scale interfaces with rare-earth ion (REI) doped crystals. First, we focus on developing a theoretical understanding of microwave-to-optical transducers. Based on coupled mode theories, we derive a clean theoretical result of the on-resonance transduction model. This allows us to condense the relevant material properties for transduction into a single parameter, effective \u03c7\u207d\u00b2\u207e, describing the strength of the non-linearities provided by the rare-earth ion materials. Next, we designed, fabricated, and measured the chip under cryogenic temperatures, where percent-level efficiency and single-photon level of added noise referred to the input is achieved. To further demonstrate the unique advantage of atom-based platforms, we perform two transducer interference experiments, showing the scalability and capacity towards transducer-assisted remote entanglement of superconducting quantum bits. Lastly, with large microwave cooperativities achieved, we observe novel quantum electrodynamics enabled by controllable initialization of the excited-state spin system. By initializing the spins into spin-down and spin-up states, we observe collectively induced transparency and periodic superradiant emissions, respectively. Simulations are developed to explain the experimental results.
\r\n\r\nThese results establish REI doped crystals as a highly competitive platform for microwave-optical quantum interfaces and pave the way toward remote transducer-assisted entanglement of superconducting quantum machines.
", "doi": "10.7907/03kg-x059", "publication_date": "2025", "thesis_type": "phd", "thesis_year": "2025" }, { "id": "thesis:16347", "collection": "thesis", "collection_id": "16347", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04102024-171434556", "primary_object_url": { "basename": "Mi_thesis_final.pdf", "content": "final", "filesize": 42530696, "license": "other", "mime_type": "application/pdf", "url": "/16347/1/Mi_thesis_final.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Many-Body Cavity Quantum Electrodynamics and Spin Dynamics with an Ensemble of Rare-Earth Ions", "author": [ { "family_name": "Lei", "given_name": "Mi", "orcid": "0009-0001-5484-7982", "clpid": "Lei-Mi" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Endres", "given_name": "Manuel A.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Refael", "given_name": "Gil", "orcid": "0009-0007-4566-8441", "clpid": "Refael-G" }, { "family_name": "Yao", "given_name": "Norman Y.", "orcid": "0000-0003-0194-7266", "clpid": "Yao-Norman-Y" } ], "local_group": [ { "literal": "Institute for Quantum Information and Matter" }, { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Studying and controlling light-matter and matter-matter interactions is a central theme in quantum physics and provides the foundation for quantum applications. Rare-earth ions (REIs) doped in solids are promising candidates for engineering scalable quantum technologies, such as quantum memories and quantum transducers, and for exploring emerging fundamental phenomena. This is because REIs have highly stable optical and spin transitions at cryogenic temperatures, and as a solid-state platform, they are compatible for integrating with quantum devices using well-established semiconductor manufacturing techniques.
\r\n\r\nThis thesis is centered on nanophotonic devices coupling to an ensemble of REIs. To explore the light-matter interaction, we build a light-matter interface by coupling an inhomogeneously broadened ensemble of ytterbium-171 doped in yttrium orthovanadate to a nanophotonic cavity with high cooperativity. In this many-body cavity quantum electrodynamics (cavity QED) system, we observe the appearance of a narrow transparency window in the cavity reflection spectrum under optical driving (collectively induced transparency, CIT). This phenomenon results from the destructive interference between pairs of two-level emitters across the inhomogeneous line and the saturation of resonant ions. Furthermore, coherent excitation of the system within this transparency window enables us to observe highly nonlinear optical emission, spanning from fast superradiance to slow subradiance. To study matter-matter interactions, we shift the focus to the strongly interacting spins. These spins feature clock transitions and pure spin exchange interactions, leading to comparable magnitudes of interaction strength and on-site disorder. We characterize and control the many-body dynamics via Hamiltonian engineering and population initialization. Furthermore, we observe the emergence of robust subharmonic oscillations under Floquet driving, providing evidence for the presence of a discrete time crystal.
\r\n\r\nThe discoveries in many-body cavity QED enable new mechanisms for achieving slow light and frequency referencing, and they provide potential for superradiant lasers. Meanwhile, our studies on spin dynamics showcase REIs as a promising platform for the study of many-body physics, with potential applications in quantum sensing and quantum simulations. In general, our findings deepen the understanding for a disordered quantum system and offer valuable insights for development of quantum applications.
", "doi": "10.7907/gx1e-en28", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:16317", "collection": "thesis", "collection_id": "16317", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03062024-043923772", "primary_object_url": { "basename": "Zheng_Tianzhe_2024_final.pdf", "content": "final", "filesize": 20073003, "license": "other", "mime_type": "application/pdf", "url": "/16317/1/Zheng_Tianzhe_2024_final.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Reconfigurable Metasurfaces in Nanoelectromechanical and Silicon-Organic Systems", "author": [ { "family_name": "Zheng", "given_name": "Tianzhe", "orcid": "0000-0001-7058-5196", "clpid": "Zheng-Tianzhe" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry", "orcid": "0000-0003-1783-1380", "clpid": "Vahaha-K" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Scherer", "given_name": "Axel", "orcid": "0000-0002-2160-9064", "clpid": "Scherer-A" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Over the past decade, metasurfaces, a technology referring to 2D or 3D engineered nanostructures, has demonstrated itself as a groundbreaking solution for creating compact and multifunctional optical devices. Moreover, the integration of metasurfaces with various modulation techniques enables compact yet high-performance active optical systems. In this thesis I explore various optical modes in engineered nanostructures and apply different design techniques to improve the amplitude and phase response of free-space modulators.
\r\n\r\nIn Chapter 1 and 2, we first briefly introduce the concept of reconfigurable metasurfaces and its state of art. Then we introduce several nanophotonic concepts that will be used frequently in later projects and discuss the potential directions to improve modulator's performance.
\r\n\r\nIn Chapter 3, we find that the dual-mode resonant metasurfaces could improve the phase response in the nanoelectromechanical system(NEMS). The interaction between the quasi-bond state in the continuum and guided mode resonance boosts the phase response up to 144 degrees.
\r\n\r\nIn Chapter 4, the design target is to utilize the high-Q mode to decrease the driving voltage of the NEMS system to CMOS level. Motivated by the low-index confinement property of the slot mode, the device achieves over 10% reflection amplitude modulation with only 1.5V in the experiment. In addition, by adding a bottom gold mirror, 1.8\u03c0 phase response is numerically observed. Based on the success of this device, we propose a design that could achieve subwavelength wavefront control. As a example, we show a 3-pixel optical beam deflector with 75% diffraction efficiency.
\r\n\r\nIn Chapter 5, we extend the use of the slot mode into silicon-organic hybrid devices. The utilization of the slot mode achieves efficient electro-optic tuning under 17V in free space with a MHz modulation speed. We also explored various methods to enhance its phase response and discuss its feasibility. The spatial phase modulation design is also proposed with a 12-period supercell pixel. The beam deflector achieves 70% diffraction efficiency numerically.
\r\n\r\nIn Chapter 6, we bring this dissertation to a close and outline potential directions for future research.
\r\n\r\nThis thesis provides a foundation for the development of high-resolution and power-efficient one-dimensional spatial light modulators and showcases the potential of reconfigurable metasurfaces.
", "doi": "10.7907/2kmq-da15", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:16211", "collection": "thesis", "collection_id": "16211", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10202023-123922325", "primary_object_url": { "basename": "PhD_Thesis.pdf", "content": "final", "filesize": 52124772, "license": "other", "mime_type": "application/pdf", "url": "/16211/1/PhD_Thesis.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Single Rare-Earth Ions in Solid-State Hosts: A Platform for Quantum Networks", "author": [ { "family_name": "Ruskuc", "given_name": "Andrei", "orcid": "0000-0001-7684-7409", "clpid": "Ruskuc-Andrei" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Endres", "given_name": "Manuel A.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Hutzler", "given_name": "Nicholas R.", "orcid": "0000-0002-5203-3635", "clpid": "Hutzler-N-R" } ], "local_group": [ { "literal": "Institute for Quantum Information and Matter" }, { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Solid-state defects have emerged as leading candidates for quantum network nodes due to their compatibility with scalable device engineering and local nuclear spins for quantum processing. Rare-earth ions in crystalline hosts are particularly attractive due to their long optical and spin coherence times at cryogenic temperatures. However, until recently, detection and utilization of single rare-earth ions in quantum technologies has been hindered by their inherently weak optical transitions. In this thesis I present progress towards realizing a novel quantum network node architecture using single \u00b97\u00b9Yb\u00b3\u207a ions in YVO\u2084, coupled to a nanophotonic cavity.
\r\n\r\nFirst, we demonstrate coherent operation of single \u00b97\u00b9Yb\u00b3\u207a ions as optically addressed qubits. To do this, we leverage first order insensitivity of optical and spin transitions to electric and magnetic fields, thereby protecting the qubits from environmental noise. We demonstrate initialization, high fidelity control and readout of a hyperfine spin qubit with long quantum storage times. We also characterize the optical transitions and find a lifetime-limited echo coherence, thereby enabling a coherent spin-photon interface.
\r\n\r\nNext, we focus on realizing an auxiliary quantum register. The high-fidelity spin control of our \u00b97\u00b9Yb\u00b3\u207a qubit is leveraged to access local nuclear spins. These spins comprise a dense ensemble which serves as a deterministic quantum resource. We utilize Hamiltonian engineering to generate tailored interactions, enabling polarization, coherent control and preparation of many-body nuclear spin states. Finally, we implement a spin-wave based memory protocol and demonstrate storage and retrieval of quantum states.
\r\n\r\nMoving beyond a single quantum node, in the final section of this thesis we will realize a small-scale quantum network using this platform. As a first step we demonstrate time-resolved quantum interference between photons emitted by ions in two separate devices. Then, we demonstrate a novel heralded entanglement protocol which incorporates optical dynamical decoupling and frequency erasure via precise photon detection. This protocol counteracts both static and dynamic inhomogeneity in the ions\u2019 optical transition frequencies, thereby enabling entanglement generation between any pair of qubits in a scalable fashion.
\r\n\r\nThese results showcase single rare-earth ions as a promising platform for the future quantum internet.
", "doi": "10.7907/ecn2-pp53", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:16164", "collection": "thesis", "collection_id": "16164", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08232023-220808049", "primary_object_url": { "basename": "20230913 - Roberts G - Thesis.pdf", "content": "final", "filesize": 18708521, "license": "other", "mime_type": "application/pdf", "url": "/16164/6/20230913 - Roberts G - Thesis.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Design, Realization, and Applications of 3D Multifunctional Nanophotonics", "author": [ { "family_name": "Roberts", "given_name": "Gregory David", "orcid": "0009-0002-0720-3938", "clpid": "Roberts-Gregory-David" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Bruno", "given_name": "Oscar P.", "orcid": "0000-0001-8369-3014", "clpid": "Bruno-O-P" }, { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Metaoptics leverages electromagnetic phenomena and the advanced abilities of modern nanofabrication to replicate traditional optical devices in a fraction of the thickness and to realize novel, compact, multifunctional devices with no known bulk equivalent. Motivated by the expanding role of optics in modern technologies, this field has seen a rise in design techniques for realizing increasingly powerful photonic structures. Three-dimensional (3D) devices, with refractive index distributions patterned at subwavelength scales, represent an enormous design space capable of achieving highly efficient, free space, multifunctional structures. By utilizing a gradient-based, iterative optimization algorithm, a technique for nanophotonic inverse design, we demonstrate scattering structures with unique responses to all the fundamental properties of light. The algorithm is constrained such that resulting devices can be made with realistic multilayer fabrication processes. We present dielectric structures that can be placed directly on top of image sensor arrays and sort light to different pixels based on its wavelength, polarization, and angular momentum, thus enabling efficient and exotic camera technologies. The following work contains fabrication and measurement of 3D devices in the mid-infrared, practical evaluations of devices for visible light imaging applications, and visualizations of underlying structure of photonic design optimization problems.
", "doi": "10.7907/1r1w-0234", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:14579", "collection": "thesis", "collection_id": "14579", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05152022-181826611", "type": "thesis", "title": "Microwave-to-Optical Transduction Using Rare-Earth Ions", "author": [ { "family_name": "Rochman", "given_name": "Jake Herschel Lebi", "orcid": "0000-0002-8475-3389", "clpid": "Rochman-Jake-Herschel-Lebi" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Schwab", "given_name": "Keith C.", "orcid": "0000-0001-8216-4815", "clpid": "Schwab-K-C" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "Institute for Quantum Information and Matter" }, { "literal": "div_eng" } ], "abstract": "Superconducting qubits that operate at microwave frequencies are one of the most promising platforms for quantum information processing. However, connecting distant processors with microwave photons is challenging since microwave photons suffer from thermal noise and large propagation losses in room temperature components.
\r\n\r\nConversely, optical photons within the telecommunications band are known to have extremely low loss in optical fiber and the thermal noise is minuscule at room temperature. In order to interface superconducting qubits with room temperature optical photons, a quantum transducer is required that can convert photons between microwave and optical frequencies.
\r\n\r\nThis thesis describes the development of a microwave-to-optical transducer using an ensemble of erbium ions, doped within a yttrium orthovanadate crystal, that are simultaneously coupled to a superconducting microwave resonator and a photonic crystal optical resonator. The erbium ions have spin transitions that couple to the microwave resonator and optical transitions at telecom wavelengths that couple to the optical resonator.
", "doi": "10.7907/4h2f-wj87", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:14344", "collection": "thesis", "collection_id": "14344", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08272021-165922711", "type": "thesis", "title": "Multifunctional Volumetric Metaoptics", "author": [ { "family_name": "Ballew", "given_name": "Conner Kiley", "orcid": "0000-0003-4854-8342", "clpid": "Ballew-Conner-Kiley" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" }, { "family_name": "Bouman", "given_name": "Katherine L.", "orcid": "0000-0003-0077-4367", "clpid": "Bouman-K-L" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Optical systems are often comprised of modular arrangements of components, and the improvement of these systems has historically leaned on the precise manufacturing and alignment of the comprising elements. This provides an intuitive pathway to optical design, but ultimately yields systems that are far bulkier than required by the laws of physics. It is often the case that the required degrees of freedom to achieve complex tasks is present within dielectric volumes that are only several wavelengths per side, and these degrees of freedom can be accessed by patterning the dielectric volume with subwavelength resolution. Even in such small volumes, all of the fundamental properties of light (wavelength, polarization, k-vector) can be controlled which opens the possibility for extremely multifunctional, compact image sensor elements. The determination of the refractive index distribution of these devices has historically been a challenging inverse-design problem, and the fabrication of 3D dielectric devices is a challenge unique to different regimes of the electromagnetic spectrum. This thesis utilizes current state-of-the-art optimization techniques to design multifunctional volumetric devices, and theoretically expands upon the techniques to facilitate the optimization of high index contrast structures. Multiple microwave prototypes are measured, devices operating at terahertz frequencies are fabricated using silicon micromachining, and optical devices with resolutions achievable with CMOS processing techniques are studied for next-generation camera sensors.
", "doi": "10.7907/dn7h-6r72", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:14140", "collection": "thesis", "collection_id": "14140", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05112021-170331252", "primary_object_url": { "basename": "Han_PhD_Thesis_Caltech_2021_May_11th.pdf", "content": "final", "filesize": 26607848, "license": "other", "mime_type": "application/pdf", "url": "/14140/1/Han_PhD_Thesis_Caltech_2021_May_11th.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Dielectric Metasurfaces for Integrated Imaging Devices and Active Optical Elements", "author": [ { "family_name": "Kwon", "given_name": "Hyounghan", "orcid": "0000-0002-9257-687X", "clpid": "Hyounghan-Kwon" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" }, { "family_name": "Atwater", "given_name": "Harry Albert", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Optical dielectric metasurfaces have shown great advances in the last two decades and become promising candidates for next-generation free-space optical elements. In addition to their compatibility with scalable semiconductor fabrication technology, metasurfaces have provided new and efficient ways to manipulate diverse characteristics of light. In this thesis, we demonstrate the potential of dielectric metastructures in the realization of compact imaging devices, reconfigurable optical elements, and multi-layer inverse-designed metasurfaces. With the metasurfaces\u2019 extreme capability to simultaneously control phase and polarization, we first showcase their potential toward optical field imaging applications. In this regard, we demonstrate a system of dielectric metasurfaces and designed random metasurfaces for single-shot phase gradient microscopes and computational complex field imaging system, respectively. Then, we propose nano-electromechanically tunable resonant dielectric metasurfaces as a general platform for active metasurfaces. For example, we demonstrate two different types of the phase and amplitude modulators. While one utilizes resonant eigenmodes in the lattice such as leaky guided mode resonances and bound-states in the continuum modes, the other is based on the high-Q Mie resonances in the dielectric nanostructures where symmetry is broken. In addition to the modulation of the phase and amplitude, we also show tuning of strong chiroptical responses in dielectric chiral metasurfaces. Next, we experimentally demonstrate inverse-designed multi-layer metasurfaces. Not only do they provide increased degree of freedom in the design space, but also overcome limits of conventional design methods of the metasurfaces. Finally, we summarize the presented works and conclude this thesis with a brief outlook on what aspects of the metasurfaces can be important for their real-world applications in the future and what challenges and opportunities remain.
", "doi": "10.7907/j08n-0q77", "publication_date": "2021", "thesis_type": "phd", "thesis_year": "2021" }, { "id": "thesis:13845", "collection": "thesis", "collection_id": "13845", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08042020-093945451", "type": "thesis", "title": "From Metasurfaces to Compact Optical Metasystems", "author": [ { "family_name": "Faraji Dana", "given_name": "Mohammad Sadegh", "orcid": "0000-0002-8012-1253", "clpid": "Faraji-Dana-Mohammad-Sadegh" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" }, { "family_name": "Wang", "given_name": "Lihong", "orcid": "0000-0001-9783-4383", "clpid": "Wang-Lihong" }, { "family_name": "Yariv", "given_name": "Amnon", "clpid": "Yariv-A" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Optical metasurfaces are a class of ultra-thin diffractive optical elements, which can control different properties of light such as amplitude, phase, polarization and direction at various wavelengths. The compatibility of optical metasurfaces with standard micro- and nano-fabrication processes makes them highly-suitable for realization of compact and planar form optical devices and systems. In addition, optical metasurfaces have achieved unique and unprecedented functionalities not possible by conventional diffractive or refractive optical elements. In this thesis, after a short review on the history and state of the art optical metasurfaces, I will discuss the systems consisting of optical metasurfaces, called optical meta-systems, which allow for implementations of complicated optical functions, such as wide field of view imaging and projection, tunable cameras, retro-reflection, phase-imaging, multi-color imaging, etc. Thereafter, the concept of folded metasurface optics is introduced and a compact folded metasurface spectrometer is showcased to demonstrate how the folded meta-systems can be designed, fabricated and practically utilized for real-life applications. Furthermore, different approaches for implementation of miniaturized hyperspectral imagers are investigated, among which the folded metasurface optics and a computational scheme using a random metasurface mask will be highlighted. Other potentials of optical metasurfaces achieved by the employment of optimization techniques to improve their multi-functional performances, as well as example applications in realizing optical vortex cornographs are studied. Finally, I will conclude the dissertation with an outlook on further applications of optical metasurfaces, where they can surpass the performance of current optical devices and systems and what limitations are still to be overcome before we can expect their wide-spread applications in our daily life.
", "doi": "10.7907/kvsy-ve81", "publication_date": "2021", "thesis_type": "phd", "thesis_year": "2021" }, { "id": "thesis:13673", "collection": "thesis", "collection_id": "13673", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04122020-055837611", "primary_object_url": { "basename": "CW_thesis.pdf", "content": "final", "filesize": 175792073, "license": "other", "mime_type": "application/pdf", "url": "/13673/115/CW_thesis.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "On-Chip Photonic Devices for Coupling to Color Centers in Silicon Carbide", "author": [ { "family_name": "Wang", "given_name": "Chuting", "orcid": "0000-0002-3711-682X", "clpid": "Wang-Chuting" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Painter", "given_name": "Oskar J.", "clpid": "Painter-O" }, { "family_name": "Minnich", "given_name": "Austin J.", "clpid": "Minnich-A-J" }, { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Optical quantum networks are important for global use of quantum computers, and secure quantum communication. Those networks require storage devices for synchronizing or making queues of processing transferred quantum information. Practical quantum information networks should minimize loss of transmitted data (photons) and have high efficiency mapping when writing data on memories (solid state qubits). This requires strong light-matter interaction that is enabled by coupling qubits to optical cavities.
\r\n\r\nThe first half of the thesis focuses on emerging candidates for promising qubits in silicon carbide (SiC). The optical and quantum properties of these color centers are discussed with focus on divacancies in 4H-SiC due to their long spin coherence time. Optically detected magnetic resonance of divacancies is shown, an essential technique for reading out the qubit state using the intensity of optical emission.
\r\n\r\nThe second half of the thesis focuses on hybrid photonic devices for coupling to silicon carbide qubits. Hybrid devices are made of another layer of high refractive index material other than the qubit hosting material. Evanescent coupling to qubits close to the surface can be achieved without damaging the host material. Mainly the silicon (Si) on 4H-SiC hybrid ring resonator architecture is discussed starting from design, simulation to fabrication. The fabrication includes Si membrane transfer that is an important step to create a light confining layer on 4H-SiC. The final ring resonator device shows quality factors as high as 23000.
", "doi": "10.7907/m2p0-6t37", "publication_date": "2020", "thesis_type": "phd", "thesis_year": "2020" }, { "id": "thesis:13759", "collection": "thesis", "collection_id": "13759", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06012020-134801698", "primary_object_url": { "basename": "Craiciu_Ioana_2020.pdf", "content": "final", "filesize": 33061620, "license": "other", "mime_type": "application/pdf", "url": "/13759/1/Craiciu_Ioana_2020.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Quantum Storage of Light Using Nanophotonic Resonators Coupled to Erbium Ion Ensembles", "author": [ { "family_name": "Craiciu", "given_name": "Ioana", "orcid": "0000-0002-8670-0715", "clpid": "Craiciu-Ioana" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Endres", "given_name": "Manuel A.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "local_group": [ { "literal": "Institute for Quantum Information and Matter" }, { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "This thesis presents on-chip quantum storage of telecommunication wavelength light using nanophotonic resonators coupled to erbium ions. Storage of light in an optical quantum memory has applications in quantum information and quantum communication. For example, long distance quantum communication using quantum repeater protocols is enabled by quantum memories. Efficient and broadband quantum memories can be made from resonators coupled to ensembles of atoms. Like other rare earth ions, erbium is appealing for quantum applications due to its long optical and hyperfine coherence times in the solid state at low temperatures. However, erbium is unique among rare earth ions in having an optical transition in the telecommunication C band (1540 nm), making it particularly appealing for quantum communication applications. In this work, we use nano-scale resonators coupled to erbium-167 ions in yttrium orthosilicate crystals (167Er 3+:Y2SiO5).
\r\n\r\nWe demonstrate quantum storage in two types of resonators. In a nanobeam photonic crystal resonator milled directly in 167Er 3+:Y2SiO5, we show storage of weak coherent states using the atomic frequency comb protocol. The storage fidelity for single photon states is estimated to be at least 93.7% ± 2.4% using decoy state analysis, Storage of up to 10 μs and multimode storage are demonstrated. Using a hybrid amorphous silicon 167Er 3+:Y2SiO5 resonator and on-chip electrodes, we demonstrate a multifunctional memory using the atomic frequency comb protocol with DC Stark shift control. In addition dynamic control of memory time, Stark shift control allows modifications to the frequency and bandwidth of stored light. We show tuning of the output pulse by ± 20 MHz relative to the input pulse, and broadening of the pulse bandwidth by more than a factor of three. The storage efficiency in both devices was limited to < 1%.
\r\n\r\nOn the way to these results, we describe 167Er 3+:Y2SiO5 spectroscopy measurements including optical coherence times and hyperfine lifetimes below 1 K, and we estimate the linear DC stark shift along two crystal directions. The design and fabrication of the on-chip resonators is presented. We discuss the limitations to storage time and efficiency, including superhyperfine coupling and resonator parameters, and we outline a path forward for improving the storage efficiency in these types of devices.
", "doi": "10.7907/yn6n-7x40", "publication_date": "2020", "thesis_type": "phd", "thesis_year": "2020" }, { "id": "thesis:11508", "collection": "thesis", "collection_id": "11508", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05112019-120905666", "primary_object_url": { "basename": "Mahsa_thesis_5_8_2019.pdf", "content": "final", "filesize": 142818215, "license": "other", "mime_type": "application/pdf", "url": "/11508/2/Mahsa_thesis_5_8_2019.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Dielectric Metasurfaces from Fundamentals to Applications", "author": [ { "family_name": "Kamali", "given_name": "Seyedeh Mahsa", "orcid": "0000-0002-6968-811X", "clpid": "Kamali-Seyedeh-Mahsa" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" }, { "family_name": "Atwater", "given_name": "Harry Albert", "clpid": "Atwater-H-A" }, { "family_name": "Wang", "given_name": "Lihong", "clpid": "Wang-Lihong" }, { "family_name": "Minnich", "given_name": "Austin J.", "clpid": "Minnich-A-J" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "In the past few decades, the advancements in nanotechnology have significantly altered many fields of science and technology, especially electronics and integrated photonics. Free-space optics, on the other hand, has remained mostly unaffected, and even today \"optics\" reminds us of carefully shaped and polished pieces of various types of glasses and crystals lumped into lenses and beam shapers. Several of these devices are then combined into more complicated optical systems like microscopes and pulse shapers that are expensive, bulky, sensitive to various environmental factors, and require several alignment steps. This thesis contains my work on designing and utilizing structures engineered at the nano-scale, which are called metasurfaces, to implement compact optical elements and systems with capabilities beyond those of conventional refractive and diffractive optics. My contributions to this field are two-fold: I have developed and contributed to the development of new concepts that take metasurfaces beyond conventional difractive optics in various aspects, in addition to paradigm changing platforms for optical element and system design. Here, I first give an overview and a brief history about optical metasurfaces. Next I discuss the unprecedented capabilities of metasurfaces in controlling light based on its degrees of freedom like illumination angle and polarization. Then, I will focus on various novel metasurface platforms of conformal and tunable metasurfaces, 3D metasurface beam shapers, and integrated metasurfaces. I conclude with an outlook on future potentials and challenges that need to be overcome for realizing their wide-spread applications.", "doi": "10.7907/TPN1-XA53", "publication_date": "2019", "thesis_type": "phd", "thesis_year": "2019" }, { "id": "thesis:11481", "collection": "thesis", "collection_id": "11481", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04222019-151834122", "type": "thesis", "title": "Metasurfaces: Beyond Diffractive and Refractive Optics", "author": [ { "family_name": "Arbabi", "given_name": "Ehsan", "orcid": "0000-0002-5328-3863", "clpid": "Arbabi-Ehsan" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Yariv", "given_name": "Amnon", "clpid": "Yariv-A" }, { "family_name": "Tai", "given_name": "Yu-Chong", "clpid": "Tai-Yu-Chong" }, { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Optical metasurfaces are a category of thin diffractive optical elements, fabricated using the standard micro- and nano-fabrication techniques. They provide new ways of controlling the flow of light based on various properties such as polarization, wavelength, and propagation direction. In addition, their compatibility with standard micro-fabrication techniques and compact form factor allows for the development of several novel platforms for the design and implementation of various complicated optical elements and systems. In this thesis, I first give a short overview and a brief history of the works on optical metasurfaces. Then I discuss the capabilities of metasurfaces in controlling the polarization and phase of light, and showcase their potential applications through the cases of polarimetric imaging and vectorial holography. Then, a discussion of the chromatic dispersion in optical metasurfaces is given, followed by three methods that can be utilized to design metasurfaces working at multiple discrete wavelengths. As a potential application of such metasurfaces, I present results of using them as objective lenses in two-photon microscopy. In addition, I discuss how metasurfaces enable the at-will control of chromatic dispersion in diffractive optical elements, demonstrate metasurfaces with controlled dispersion, and provide a discussion of their limitations. Integration of multiple metasurfaces into metasystems allows for implementation of complicated optical functions such as imaging and spectrometry. In this regard, I present several examples of how such metasystems can be designed, fabricated, and utilized to provide wide field of view imaging and projection, microelectromechanically tunable lenses, optical spectrometers, and retroreflectors. I conclude with an outlook on where metasurfaces can be most useful, and what limitations should be overcome before they can find wide-spread application.
", "doi": "10.7907/EQEY-KZ52", "publication_date": "2019", "thesis_type": "phd", "thesis_year": "2019" }, { "id": "thesis:11677", "collection": "thesis", "collection_id": "11677", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06032019-143215628", "primary_object_url": { "basename": "Huan_YanQi_2019_WebUploadVer.pdf", "content": "final", "filesize": 17680847, "license": "other", "mime_type": "application/pdf", "url": "/11677/1/Huan_YanQi_2019_WebUploadVer.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Efficient Coupling of Tapered Optical Fibers to Silicon Nanophotonic Waveguides on Rare-Earth Doped Crystals", "author": [ { "family_name": "Huan", "given_name": "Yan Qi", "orcid": "0000-0002-6505-7150", "clpid": "Huan-Yan-Qi" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "None", "given_name": "None" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Quantum networks are a rapidly developing field of quantum information processing that have the potential to enable long-range entanglement between future quantum computers as well as the implementation of secure communication through quantum key distribution. Two key components of such networks are quantum memories to store entangled photon pairs for use in the quantum repeater protocol and quantum light-matter interfaces to efficiently interconvert between stationary qubits and flying qubits in the form of photons. Rare-earth ion-doped crystals are a promising solid-state platform that show promise for both of these applications due to their long optical and spin coherence times. Due to their relatively weak optical transitions, rare-earth ions have been coupled with nanophotonic resonators to enhance their transition strengths, with past work in the Faraon group utilizing focused ion beam milled photonic crystal resonators with 45-degree angled couplers to couple light in and out. Such resonators have the disadvantage of requiring manual alignment to fabricate, and the couplers are also relatively inefficient which limits the performance of such devices. It is therefore desirable to move towards silicon photonics, where mature techniques such as electron-beam lithography can allow for scalable fabrication of nanophotonic cavities together with high coupling efficiencies.
\r\n\r\nIn this thesis, we demonstrate significant progress towards the usage of acid-etched tapered optical fibers as an efficient interface for coupling light into tapered silicon nanophotonic waveguides. We show comprehensive simulations of the taper geometries required to achieve adiabatic coupling with theoretical efficiencies of more than 99%, and design a silicon photonic crystal mirror to be used in the measurement of the fiber-waveguide coupling efficiency. We then optimize the hydrofluoric acid fiber etching process and demonstrate the ability to make tapered fibers which are 200 microns long with a taper half-angle of 2 degrees and a tip diameter of 50 nm. Using these tapered fibers to couple light into tapered silicon waveguides fabricated using electron-beam lithography shows a moderately high coupling efficiency of 11.4% with the potential for improvement. This method of tapered fiber coupling shows promise to be integrated into silicon nanophotonic resonators on rare-earth ion doped crystals and allow for highly efficient quantum memories and quantum light-matter interfaces in the solid-state.
", "doi": "10.7907/QXEA-0C75", "publication_date": "2019", "thesis_type": "senior_major", "thesis_year": "2019" }, { "id": "thesis:11421", "collection": "thesis", "collection_id": "11421", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03132019-062905529", "primary_object_url": { "basename": "Kindem_Jonathan_2019.pdf", "content": "final", "filesize": 18204037, "license": "other", "mime_type": "application/pdf", "url": "/11421/1/Kindem_Jonathan_2019.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Quantum Nanophotonics with Ytterbium in Yttrium Orthovanadate", "author": [ { "family_name": "Kindem", "given_name": "Jonathan Miners", "orcid": "0000-0002-7737-9368", "clpid": "Kindem-Jonathan-Miners" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Painter", "given_name": "Oskar J.", "clpid": "Painter-O" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Hutzler", "given_name": "Nicholas R.", "clpid": "Hutzler-N-R" }, { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "Institute for Quantum Information and Matter" }, { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Quantum light-matter interfaces that can reversibly map quantum information between photons and atoms are essential for building future quantum networks. Crystals doped with rare-earth ions (REIs) are an attractive solid-state platform for such light-matter interfaces due to their exceptional optical and spin coherence properties at cryogenic temperatures. Building scalable REI-based technology has proven to be challenging due to the inherently weak coupling of REIs with light. This thesis explores the integration of REIs with nanophotonic resonators to overcome this weak light-matter interaction and enable efficient, scalable quantum light-matter interfaces. Specifically, this work focuses on the development of quantum nanophotonics with ytterbium in yttrium orthovanadate.
\r\n \r\nThis thesis begins with an introduction to a nanophotonic platform based on photonic crystal cavities fabricated directly in rare-earth host materials and highlights the initial successes of this platform with neodymium-doped materials. This motivates an examination of the optical and spin coherence properties of 171Yb:YVO4, a REI material that was previously unexplored for quantum technology applications. This material is found to have strong optical transitions compared to other REI-doped materials, a simple energy level structure, and long optical and spin coherence lifetimes.
\r\n\r\nThe focus then turns to the detection and coherent manipulation of single ytterbium ions coupled to nanophotonic cavities. The Purcell-enhancement in these cavities enables efficient optical detection and spin initialization of individual ytterbium ions. We identify ions corresponding to different isotopes of ytterbium and show that the coupling of electron and nuclear spin in ytterbium-171 at zero-field gives rise to strong electron-spin-like transitions that are first-order insensitive to magnetic field fluctuations. This allows for coherent microwave control and the observation of long spin coherence lifetimes at temperatures up to 1 K. We then make use of the optical selection rules and energy structure of 171Yb:YVO4 to demonstrate high-fidelity single-shot optical readout of the spin state. These results establish nanophotonic devices in 171Yb:YVO4 as a promising platform for solid-state quantum light-matter interfaces.
", "doi": "10.7907/Q40T-8907", "publication_date": "2019", "thesis_type": "phd", "thesis_year": "2019" }, { "id": "thesis:10442", "collection": "thesis", "collection_id": "10442", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:09202017-124555409", "primary_object_url": { "basename": "Horie_Yu_2018.pdf", "content": "final", "filesize": 59827475, "license": "other", "mime_type": "application/pdf", "url": "/10442/1/Horie_Yu_2018.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Controlling the Flow of Light Using High-Contrast Metastructures", "author": [ { "family_name": "Horie", "given_name": "Yu", "orcid": "0000-0001-7083-1270", "clpid": "Horie-Yu" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "A new class of planar optical components and devices has emerged using subwavelength metastructures with a strong contrast in refractive indices. High-contrast metastructures have shown promises to manipulate optical fields in an extraordinary way and to replace conventional bulky optical elements by their low-profile analogs, typically with subwavelength-scale features. We elucidate the underlying principle, how these seemingly low-profile geometries render unique optical responses, using the coupled-mode analysis in a multimode waveguide. Moreover, strong field localization in high-index structures allows us to interpret each single element in the metastructures as a low-quality-factor resonator (or a localized scatterer), permitting us to realize designer surface that shapes phase, amplitude, and polarization of light in free space, also known as an optical metasurface. The remainder of the thesis is devoted to explore novel applications in optics using high-contrast metastructures. One of the particularly interesting applications is to use them in an optical resonator. Specifically, we demonstrate to incorporate high-contrast subwavelength grating reflectors and dielectric metasufaces in a vertical Fabry\u2013Perot cavity, and show that we can flexibly tune the resonance frequency by the subwavelength patterning. With this technique, we envision the realization of compact, on-chip spectrometers when integrating them on a photodetector array. Secondly, we investigate the use of high-contrast subwavelength gratings in visible wavelengths. We perform the optimization of their geometries and demonstrate a set of RGB color filters, down to near a micrometer in the pixel size. This platform exhibits unique performances such as high efficiency, angular insensitivity, and color tunability by the design. A novel device concept is also explored, where a high-contrast subwavelength grating reflector is integrated on a silicon platform to constitute an active resonant antenna, enabling high-speed, phase-dominant modulation by means of thermo-optic effect of silicon. We demonstrate an array of such active antennas, yielding a beam deflection capability. This justifies the robustness of our device design, enabling a large-scale integration of high-speed, phase-dominant spatial light modulators. Finally, we introduce a disorder-engineered metasurface in the context of wavefront shaping. Recently, wavefront shaping with disordered media has demonstrated optical manipulation capabilities beyond those of conventional optics, but translating this class of technology into a practical use has remained challenging due to enormous amounts of information needed to be characterized as the input-output responses. As a paradigm shift, we propose the use of disorder-engineered metasurface in wavefront shaping, where the disorder is programmatically designed and makes the system characterization-free prior to use. With this approach, we demonstrate high numerical aperture focusing in an extended volume as well as wide-field fluorescence imaging with unprecedented performances.
", "doi": "10.7907/Z94X5604", "publication_date": "2018", "thesis_type": "phd", "thesis_year": "2018" }, { "id": "thesis:10096", "collection": "thesis", "collection_id": "10096", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03152017-114949088", "primary_object_url": { "basename": "Miyazono_Evan_2017.pdf", "content": "final", "filesize": 31648083, "license": "cc_by_nc_sa", "mime_type": "application/pdf", "url": "/10096/1/Miyazono_Evan_2017.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Nanophotonic Resonators for Optical Quantum Memories based on Rare-Earth-Doped Materials", "author": [ { "family_name": "Miyazono", "given_name": "Evan Tsugio", "orcid": "0000-0003-2176-0335", "clpid": "Miyazono-Evan-Tsugio" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Schwab", "given_name": "Keith C.", "clpid": "Schwab-K-C" }, { "family_name": "Scherer", "given_name": "Axel", "clpid": "Scherer-A" }, { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "Institute for Quantum Information and Matter" }, { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "The growing interest in optical quantum systems has led to the exploration of multiple platforms. Though pioneering experiments were performed in trapped atom and trapped ion systems, solid state systems show promise of being scalable and robust. Rare earth dopants in crystalline hosts are an appealing option because they possess a rich spectrum of energy levels that result from a partially filled electron orbital. While level structure varies across the period, all elements possess crystal field splittings corresponding to near infra-red or optical frequencies, as well as Zeeman and often hyperfine levels separated by radio frequency and microwave frequencies. These levels demonstrate long excited-state lifetimes and coherence times and have been used in diverse applications, including demonstrating storage of a photonic state, converting of optical to microwave photons, and manipulating a single ion as a single qubit. The ions' weak interaction with their environment results in low coupling to optical fields, which had previously required measurements with macroscopically large ensembles of ions. Coupling the ions to an optical cavity enables the use of a smaller ensemble, which is required for the development of the aforementioned technologies in an on-chip scalable architecture.
\r\n\r\nThis thesis contains recent progress towards fabricating optical micro and nanocavities coupled to ensembles of erbium ions, mainly erbium in yttrium orthosilicate. In one design, focused ion beam milling was used to create a triangular nanobeam photonic crystal cavity in a bulk erbium-doped substrate. A second design leveraged the fabrication capabilities of silicon photonics, defining amorphous silicon ring resonators using electron beam lithography and dry etching. These devices coupled evanescently to erbium ions below the ring, in the bulk substrate. Simulation, design, fabrication, and characterization of both resonators are discussed. Coupling between the ions and the resonator is demonstrated for each, and capabilities offered by these devices are described. Preliminary work implementing coherent control of erbium ions is presented. Lastly, alternative substrates are evaluated for possible future solid-state erbium systems.
", "doi": "10.7907/Z98K773F", "publication_date": "2017", "thesis_type": "phd", "thesis_year": "2017" }, { "id": "thesis:10626", "collection": "thesis", "collection_id": "10626", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01082018-145226522", "type": "thesis", "title": "Single Lens Holographic Imaging", "author": [ { "family_name": "Ding", "given_name": "Leon", "clpid": "Ding-Leon" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "None", "given_name": "None" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Metasurface phase masks offer a new way of imaging in that the lens sizes are orders of magnitude smaller and allow for batch fabrication of a large number of miniature lenses. Unfortunately, current metasurface lens technology cannot simultaneously overcome the issues of image distortion for objects far from the optical axis and chromatic aberrations. Using simulations in Matlab, we study and design a single lens holographic system using metasurface lenses to drastically reduce both off-axis distortions and chromatic aberrations. Using a single metasurface lens, we demonstrate that a high quality image can be obtained for an object with a 30\u00b0 angular diameter and 123 fractional bandwidth. We also experimentally demonstrate reduction of aberrations and 3D imaging for spare images as well as show mediocre quality reconstructed dense images.", "doi": "10.7907/PSN7-TT19", "publication_date": "2017", "thesis_type": "senior_major", "thesis_year": "2017" } ]