Jelena Notaroš

Integrated optical phased arrays (OPAs) have emerged as a promising technology for many applications due to their ability to dynamically control free-space optical beams in a compact and non-mechanical manner. However, these integrated OPAs typically have a restricted field of view (FOV), limited by grating lobes caused by large antenna pitches that are typically necessary to reduce crosstalk between the antennas in the integrated OPA. In this work, we develop and experimentally demonstrate for the first time, to the best of our knowledge, a set of integrated grating-based antennas with significantly-reduced inter-antenna crosstalk that enable half-wavelength-pitch integrated OPAs with grating-lobe-free and wide-FOV functionality. First, we derive a generalized theoretical model to describe the coupling dynamics between lossy modes in a system and use this model to analyze the coupling between antennas. Next, we design and demonstrate a set of three integrated grating-based antennas with different propagation coefficients to enable reduced inter-antenna crosstalk, successfully measuring a significant reduction from 100% to 1% coupling. Finally, using these reduced-crosstalk antennas, we develop and demonstrate a half-wavelength-pitch integrated OPA, successfully demonstrating grating-lobe-free and wide-FOV functionality. This work facilitates new functionality for high-performance integrated OPAs. This work overcomes fundamental limitations in the field of view of beam-steering integrated optical phased arrays by developing integrated optical antennas that reduce crosstalk from 100% to 1% and utilizing them to enable a half-wavelength-pitch integrated optical phased array with a wide field of view.

Spontaneously emitted photons are entangled with the electronic and nuclear degrees of freedom of the emitting atom, so interference and measurement of these photons can entangle separate matter-based quantum systems as a resource for quantum information processing. Since confinement in a single-mode facilitates the photon interference needed for generating entanglement, the dipole emission patterns relevant in spontaneous emission present a mode-matching challenge. Current demonstrations rely on bulk photon-collection and manipulation optics that suffer from large component size and system-to-system variability-factors that impede scaling to the large numbers of entangled pairs needed for quantum information processing. To address these limitations, we demonstrate a collection method that enables passive phase stability, straightforward photonic manipulation, and intrinsic reproducibility. Specifically, we engineer a waveguide-integrated grating to couple photons emitted from a trapped ion into a single optical mode within a microfabricated ion-trap chip. Using the integrated collection optic, we characterize the collection efficiency, image the ion, and detect the ion's quantum state. The integrated optic covers 2.18% of the solid angle and collects 1.97 ± 0.3% of the spontaneously emitted light incident on the grating for a total collection efficiency of 0.043% into a single-mode waveguide. This proof-of-principle demonstration lays the foundation for leveraging the inherent stability and reproducibility of integrated photonics to create, manipulate, and measure multipartite quantum states in arrays of quantum emitters.

Trapped ions are a promising modality for quantum systems, with demonstrated utility as the basis for quantum processors and optical clocks. However, traditional trapped-ion systems are implemented using complex free-space optical configurations, whose large size and susceptibility to vibrations and drift inhibit scaling to large numbers of qubits. In recent years, integrated-photonics-based systems have been demonstrated as an avenue to address the challenge of scaling trapped-ion systems while maintaining high fidelities. While these previous demonstrations have implemented both Doppler and resolved-sideband cooling of trapped ions, these cooling techniques are fundamentally limited in efficiency. In contrast, polarization-gradient cooling can enable faster and more power-efficient cooling and, therefore, improved computational efficiencies in trapped-ion systems. While free-space implementations of polarization-gradient cooling have demonstrated advantages over other cooling mechanisms, polarization-gradient cooling has never previously been implemented using integrated photonics. In this paper, we design and experimentally demonstrate key polarization-diverse integrated-photonics devices and utilize them to implement a variety of integrated-photonics-based polarization-gradient-cooling systems, culminating in the first experimental demonstration of polarization-gradient cooling of a trapped ion by an integrated-photonics-based system. By demonstrating polarization-gradient cooling using an integrated-photonics-based system and, in general, opening up the field of polarization-diverse integrated-photonics-based devices and systems for trapped ions, this work facilitates new capabilities for integrated-photonics-based trapped-ion platforms.

Trapped ions are a promising modality for quantum systems, with demonstrated utility as the basis for quantum processors and optical clocks. However, traditional trapped-ion systems are implemented using complex free-space optical configurations, whose large size and susceptibility to vibrations and drift inhibit scaling to large numbers of qubits. In recent years, integrated-photonics-based systems have been demonstrated as an avenue to address the challenge of scaling trapped-ion systems while maintaining high fidelities. While these previous demonstrations have implemented both Doppler and resolved-sideband cooling of trapped ions, these cooling techniques are fundamentally limited in efficiency. In contrast, polarization-gradient cooling can enable faster and more power-efficient cooling and, therefore, improved computational efficiencies in trapped-ion systems. While free-space implementations of polarization-gradient cooling have demonstrated advantages over other cooling mechanisms, polarization-gradient cooling has never previously been implemented using integrated photonics. In this paper, we design and experimentally demonstrate key polarization-diverse integrated-photonics devices and utilize them to implement a variety of integrated-photonics-based polarization-gradient-cooling systems, culminating in the first experimental demonstration of polarization-gradient cooling of a trapped ion by an integrated-photonics-based system. By demonstrating polarization-gradient cooling using an integrated-photonics-based system and, in general, opening up the field of polarization-diverse integrated-photonics-based devices and systems for trapped ions, this work facilitates new capabilities for integrated-photonics-based trapped-ion platforms. We design and demonstrate a variety of integrated-photonics-based polarization-gradient-cooling systems, culminating in the first experimental demonstration of trapped-ion polarization-gradient cooling using integrated photonics, facilitating new capabilities for integrated-photonics-based trapped-ion platforms.

Minimizing background optical emission originating from waveguides is critical for achieving high-sensitivity performance in integrated photonic platforms, particularly for applications in biosensing, chemical detection, environmental monitoring, and quantum sensors. These background signals, often stemming from intrinsic fluorescence (also known as autofluorescence or photoluminescence) or Raman scattering in the waveguide core or cladding, can obscure weak optical signals and limit the accuracy of integrated photonic sensors. In this work, we introduce a novel parameter-extraction technique that quantitatively separates waveguide losses and background-generation efficiency, and identifies the individual contributions of the waveguide core and cladding to the total background signal. Our method utilizes only standard photonic waveguides and requires no specialized sample preparation or auxiliary test wafers. We validate our technique experimentally by characterizing silicon-nitride waveguides across nine wafers fabricated in a 300-mm-wafer platform developed at AIM Photonics. Applying our parameter-extraction method, we demonstrate its utility in showing a clear correlation between waveguide propagation loss and fluorescence, and its sensitivity in resolving material-specific differences in Raman spectra between wafers fabricated using different processes, including those arising from hydrogen-related impurities in non-annealed cores. This work provides a practical and comprehensive tool for quantifying, diagnosing, and reducing material-specific propagation loss and background signals in integrated photonic waveguides, ultimately enabling more effective development of low-noise and low-loss photonics platforms.

Integrated optical phased arrays (OPAs), fabricated in advanced silicon-photonics platforms, enable manipulation and dynamic control of free-space light in a compact form factor, at low costs, and in a non-mechanical way. This talk will highlight our work on developing OPA-based platforms, devices, and systems that enable chip-based solutions to high-impact problems in areas including LiDAR sensing for autonomous vehicles, augmented-reality displays, 3D printing, optical trapping for biophotonics, and trapped-ion quantum engineering.

In this Letter, we design and experimentally demonstrate the first, to the best of our knowledge, integrated optical-phased-array-based (OPA-based) system that simultaneously emits and controls beams of red, green, and blue light. First, we develop this visible-spectrum-spanning integrated OPA-based system architecture and the corresponding requisite devices and fabricate the system in a 300-mm wafer-scale silicon-photonics foundry process. Next, we use the integrated OPA-based system to experimentally demonstrate simultaneous 2D beam steering at red, green, and blue wavelengths. Finally, we apply the integrated OPA-based system to display a 2D RGB image of the MIT logo. This work enables visible-spectrum-spanning functionality for emerging applications of integrated OPAs that require visible-light operation, such as displays, 3D printing, atomic quantum systems, underwater optical communications, and optogenetics.

In this work, we discuss fabrication processes, important considerations, and evaluation techniques for successful packaging of liquid crystal (LC) into silicon-photonics platforms to enable compact and power-efficient integrated LC-based modulators. First, we describe our 300-mm-wafer silicon-photonics foundry fabrication platform and chip-scale LC-packaging process. Second, we demonstrate packaging evaluation techniques for analyzing LC misalignment using both standard and polarizing microscopes. Third, we develop and validate a heat-based procedure to improve packaged LC alignment. Fourth, we study the effect of heat cycling on the integrity of integrated LC-based modulators, showing no significant performance degradation even after 1000 cycles. Finally, we demonstrate the detrimental effects of UV exposure on integrated LC-based modulator performance. This work provides essential insights to facilitate the higher-yield integration and widespread use of integrated LC-based modulators for high-density integrated systems that require compact and power-efficient modulators.

Spontaneously emitted photons are entangled with the electronic and nuclear degrees of freedom of the emitting atom, so interference and measurement of these photons can entangle separate matter-based quantum systems as a resource for quantum information processing. However, the isotropic nature of spontaneous emission hinders the single-mode photonic operations required to generate entanglement. Current demonstrations rely on bulk photon-collection and manipulation optics that suffer from environment-induced phase instability, mode matching challenges, and system-to-system variability, factors that impede scaling to the large numbers of entangled pairs needed for quantum information processing. To address these limitations, we demonstrate a collection method that enables passive phase stability, straightforward photonic manipulation, and intrinsic reproducibility. Specifically, we engineer a waveguide-integrated grating to couple photons emitted from a trapped ion into a single optical mode within a microfabricated ion-trap chip. Using the integrated collection optic, we characterize the collection efficiency, image the ion, and detect the ion's quantum state. This proof-of-principle demonstration lays the foundation for leveraging the inherent stability and reproducibility of integrated photonics to efficiently create, manipulate, and measure multipartite quantum states in arrays of quantum emitters.

Integrated Optical Phased Arrays (OPAs), fabricated in advanced silicon-photonics platforms, enable manipulation and dynamic control of free-space light in a compact form factor, at low costs, and in a non-mechanical way. This talk will highlight our work on developing OPA-based platforms, devices, and systems that enable chip-based solutions to high-impact problems in areas including LiDAR sensing for autonomous vehicles, augmented-reality displays, 3D printing, optical trapping for biophotonics, and trapped-ion quantum engineering.

Integrated optical phased arrays (OPAs) based on arrayed waveguide gratings (AWGs) enable two-dimensional (2D) beam steering through wavelength tuning. Achieving a high vertical resolution for practical applications remains challenging due to the waveguide phase errors associated with the large AWG required. Here, we present a high-resolution 65-channel AWG-assisted OPA with 5 inputs. Ultra-low loss silicon nitride waveguide technology and transverse magnetic mode operation are employed for waveguide-phase-error mitigation. A vertical resolution of 0.32° using a single input is attained with a beam width of 0.55° × 0.07° and an alias-free horizontal field of view (FOV) of 30°. By utilizing all 5 inputs, the vertical resolution can be enhanced to 0.06°. Real-time 2D beam steering over a 25° × 5° FOV is demonstrated. To our best knowledge, this work demonstrates the highest vertical resolution reported for an AWG-based OPA.

Optical phased arrays (OPAs) with arrayed waveguide gratings (AWGs) enable two-dimensional (2D) beam steering through wavelength tuning. Achieving a high vertical resolution for practical applications remains challenging due to the waveguide phase errors associated with the large AWG required. Here, we present a high-resolution 65-channel AWG-assisted OPA with 5 inputs. Ultra-low loss silicon nitride waveguide technology and transverse magnetic mode operation are employed for waveguide phase error mitigation. A vertical resolution of 0.3° using a single input is attained with a beam width of 0.55°× 0.07° and an alias-free horizontal field of view (FOV) of 30°. By utilizing all 5 inputs, the vertical resolution can be enhanced to 0.06°. Real-time 2D beam steering over a 25°× 5° FOV is demonstrated. To our knowledge, this work demonstrates the highest vertical resolution reported for an AWG-based OPA.

Optical phased arrays (OPAs) with arrayed waveguide gratings (AWGs) enable two-dimensional (2D) beam steering through wavelength tuning. Achieving a high vertical resolution for practical applications remains challenging due to the waveguide phase errors associated with the large AWG required. Here, we present a high-resolution 65-channel AWG-assisted OPA with 5 inputs. Ultra-low loss silicon nitride waveguide technology and transverse magnetic mode operation are employed for waveguide phase error mitigation. A vertical resolution of 0.3° using a single input is attained with a beam width of 0.55°× 0.07° and an alias-free horizontal field of view (FOV) of 30°. By utilizing all 5 inputs, the vertical resolution can be enhanced to 0.06°. Real-time 2D beam steering over a 25°× 5° FOV is demonstrated. To our knowledge, this work demonstrates the highest vertical resolution reported for an AWG-based OPA.

We design and demonstrate key polarization-diverse integrated-photonics devices and utilize them to implement a variety of integrated-photonics-based polarization-gradient-cooling systems, culminating in the first demonstration of polarization-gradient cooling of a trapped ion by an integrated-photonics-based system.

We design and experimentally demonstrate the first integrated optical-phased-array-based system that simultaneously emits and controls beams of red, green, and blue light, enabling visible-spectrum-spanning functionality for emerging applications of integrated optical phased arrays that require visible-light operation.

We design and experimentally demonstrate five integrated visible-light grating-based antennas with varying advanced capabilities, including the first visible-light unidirectionally-emitting grating-based antennas for integrated optical phased arrays.

We develop and characterize the first 300-mm wafer-scale platform and fabrication process for transparent and mechanically-flexible photonic wafers and chips, demonstrating high mechanical robustness, high optical transparency, and low optical distortion.

We develop and experimentally demonstrate the first reduced-crosstalk integrated grating-based optical antennas, and utilize them to enable a half-wavelength-pitch grating-lobe-free integrated optical phased array with a wide 180-degree field of view.

We introduce a novel method to identify the core and cladding contributions to background emission in integrated photonic waveguides, enabling more effective development and material optimization for low-noise and low-loss integrated photonics platforms. We validate the method by characterizing nine wafers fabricated in the AIM-Photonics platform.

Trapped ions provide a highly controlled platform for quantum sensors, clocks, simulators, and computers, all of which depend on cooling ions close to their motional ground state. Existing methods like Doppler, resolved sideband, and dark resonance cooling balance trade-offs between the final temperature and cooling rate. A traveling polarization gradient has been shown to cool multiple modes quickly and in parallel, but utilizing a stable polarization gradient can achieve lower ion energies, while also allowing more tailorable light-matter interactions in general. In this paper, we demonstrate cooling of a trapped ion below the Doppler limit using a phase-stable polarization gradient created using trap-integrated photonic devices. At an axial frequency of $2π\cdot1.45~ \rm MHz$ we achieve $\langle n \rangle = 1.3 \pm 1.1$ in $500~μ\rm s$ and cooling rates of ${\sim}0.3 \, \rm quanta/μs$. We examine ion dynamics under different polarization gradient phases, detunings, and intensities, showing reasonable agreement between experimental results and a simple model. Cooling is fast and power-efficient, with improved performance compared to simulated operation under the corresponding running wave configuration.

Integrated optical phased arrays (OPAs) have emerged as a promising technology for various applications due to their ability to dynamically control free-space optical beams in a compact and non-mechanical manner. While integrated OPAs have traditionally focused on the infrared spectrum, advancements in visible-light integrated OPAs have been relatively limited despite their potential benefits for applications such as displays, 3D printing, trapped-ion quantum systems, underwater communications, and optogenetics. Moreover, integrated visible-light grating-based optical antennas, one of the crucial devices that forms a visible-light integrated OPA, have been relatively underexplored, especially for more advanced designs. In this paper, we address this gap by providing a thorough explanation of the design principles for integrated visible-light grating-based antennas and applying them to design and experimentally demonstrate five different antennas with varying advanced capabilities, including the first visible-light unidirectionally-emitting grating-based antennas for integrated OPAs. Specifically, we develop and experimentally demonstrate integrated visible-light exponentially-emitting single-layer, uniformly-emitting single-layer, exponentially-emitting dual-layer, uniformly-emitting dual-layer, and unidirectionally-emitting dual-layer grating-based antennas. This work aims to provide a thorough design guide for integrated visible-light grating-based antennas, facilitating future widespread use of integrated OPAs for new and emerging visible-light applications.

Integrated optical phased arrays (OPAs) have enabled cutting-edge applications where optical beam steering can benefit from chip-scale integration. However, the majority of integrated OPA demonstrations to date have been limited to showing far-field beam forming and steering. There are, however, many emerging applications of integrated photonics where emission of focused light from a chip is desirable, such as in integrated optical tweezers for biophotonics, chip-based 3D printers, and trapped-ion quantum systems. To address this need, we have recently demonstrated the first near-field-focusing integrated OPAs; however, this preliminary demonstration was limited to emission at only one focal plane above the chip. In this paper, we show the first, to the best of our knowledge, spiral integrated OPAs, enabling emission of focusing beams with tunable variable focal heights for the first time. In the process, we develop the theory, explore the design parameters, and propose feed-structure architectures for such OPAs. Finally, we experimentally demonstrate an example spiral integrated OPA system fabricated in a standard silicon-photonics process, showing wavelength-tunable variable-focal-height focusing emission. This work introduces a first-of-its-kind integrated OPA architecture not previously explored or demonstrated in literature and, as such, enables new functionality for emerging applications of OPAs that require focusing operation.

Integrated optical tweezers have the potential to enable highly-compact, low-cost, mass-manufactured, and broadly-accessible optical manipulation when compared to standard bulk-optical tweezers. However, integrated demonstrations to date have been fundamentally limited to micron-scale standoff distances and, often, passive trapping functionality, making them incompatible with many existing applications and significantly limiting their utility, especially for biological studies. In this work, we demonstrate optical trapping and tweezing using an integrated OPA for the first time, increasing the standoff distance of integrated optical tweezers by over two orders of magnitude compared to prior demonstrations. First, we demonstrate trapping of polystyrene microspheres 5 mm above the surface of the chip and calibrate the trap force. Next, we show tweezing of polystyrene microspheres in one dimension by non-mechanically steering the trap by varying the input laser wavelength. Finally, we use the OPA tweezers to demonstrate, to the best of our knowledge, the first cell experiments using single-beam integrated optical tweezers, showing controlled deformation of mouse lymphoblast cells. This work introduces a new modality for integrated optical tweezers, significantly expanding their utility and compatibility with existing applications, especially for biological experiments.

Solid-state light-detection-and-ranging (LiDAR) sensors based on integrated optical phased arrays (OPAs) have shown significant promise to reduce the cost, size, weight, and power consumption associated with LiDAR for autonomous systems. However, these OPA-based LiDAR systems typically operate by rastering a single beam, generating point clouds that constitute a significant amount of data and computational burden in the process. In this paper, we develop and experimentally demonstrate a novel multi-beam solid-state OPA-based LiDAR system capable of detecting and ranging multiple targets simultaneously, passively, and without rastering. Specifically, we develop the devices, subsystems, and system architectures to realize a solid-state frequency-modulated-continuous-wave (FMCW) LiDAR system that leverages a discrete-Fourier-transform star-coupler-based OPA as a receiver and a multi-beam splitter-tree-based OPA as a transmitter. Using this multi-beam LiDAR system, we demonstrate the simultaneous detection and ranging of two targets at two different cross-range positions without rastering. Through this work, we demonstrate a new spatially-adaptive sensing modality for solid-state LiDAR that enables improved spatial awareness and promises to reduce the data deluge associated with LiDAR in autonomous systems.

Control over the amplitude, phase, and spatial distribution of visible-spectrum light underlies many technologies, but commercial solutions remain bulky, require high control power, and are often too slow. Active integrated photonics for visible light promises a solution, especially with recent materials and fabrication advances. In this review, we discuss three growing application spaces which rely on control of visible light: control and measurement of atomic quantum technologies, augmented-reality displays, and measurement and control of biological systems. We then review the commercial dynamic surfaces and bulk systems which currently provide visible-light modulation and the current state-of-the-art integrated solutions. Throughout the review we focus on speed, control power, size, optical bandwidth, and technological maturity when comparing technologies.

Integrated optical-phased-array-based platforms, devices, and systems for applications in augmented-reality displays, LiDAR sensing for autonomous vehicles, optical trapping for biophotonics, chip-based 3D printing, and trapped-ion quantum engineering will be reviewed.

Integrated optical phased arrays (OPAs), fabricated in advanced silicon-photonics platforms, enable manipulation and dynamic control of free-space light in a compact form factor, at low costs, and in a non-mechanical way. This talk will highlight our work on developing OPA-based platforms, devices, and systems that enable chip-based solutions to high-impact problems in areas including augmented-reality displays, LiDAR sensing for autonomous vehicles, optical trapping for biophotonics, 3D printing, and trapped-ion quantum engineering.

Integrated optical phased arrays (OPAs), fabricated in advanced silicon-photonics platforms, enable manipulation and dynamic control of free-space light in a compact form factor, at low costs, and in a non-mechanical way. This talk will highlight our work on developing OPA-based platforms, devices, and systems that enable chip-based solutions to high-impact problems in areas including augmented-reality displays, LiDAR sensing for autonomous vehicles, optical trapping for biophotonics, 3D printing, and trapped-ion quantum engineering.

Imagine if it were possible to create 3D objects in the palm of your hand within seconds using only a single photonic chip. Although 3D printing has revolutionized the way we create in nearly every aspect of modern society, current 3D printers rely on large and complex mechanical systems to enable layer-by-layer addition of material. This limits print speed, resolution, portability, form factor, and material complexity. Although there have been recent efforts in developing novel photocuring-based 3D printers that utilize light to transform matter from liquid resins to solid objects using advanced methods, they remain reliant on bulky and complex mechanical systems. To address these limitations, we combine the fields of silicon photonics and photochemistry to propose the first chip-based 3D printer. The proposed system consists of only a single millimeter-scale photonic chip without any moving parts that emits reconfigurable visible-light holograms up into a simple stationary resin well to enable non-mechanical 3D printing. Furthermore, we experimentally demonstrate a stereolithography-inspired proof-of-concept version of the chip-based 3D printer using a visible-light beam-steering integrated optical phased array and visible-light-curable resin, showing 3D printing using a chip-based system for the first time. This work demonstrates the first steps towards a highly-compact, portable, and low-cost solution for the next generation of 3D printers.

The field of integrated photonics has advanced rapidly due to wafer-scale fabrication, with integrated-photonics platforms and fabrication processes being demonstrated at both infrared and visible wavelengths. However, these demonstrations have primarily focused on fabrication processes on silicon substrates that result in rigid photonic wafers and chips, which limit the potential application spaces. There are many application areas that would benefit from mechanically-flexible integrated-photonics wafers, such as wearable healthcare monitors and pliable displays. Although there have been demonstrations of mechanically-flexible photonics fabrication, they have been limited to fabrication processes on the individual device or chip scale, which limits scalability. In this paper, we propose, develop, and experimentally characterize the first 300-mm wafer-scale platform and fabrication process that results in mechanically-flexible photonic wafers and chips. First, we develop and describe the 300-mm wafer-scale CMOS-compatible flexible platform and fabrication process. Next, we experimentally demonstrate key optical functionality at visible wavelengths, including chip coupling, waveguide routing, and passive devices. Then, we perform a bend-durability study to characterize the mechanical flexibility of the photonic chips, demonstrating bending a single chip 2000 times down to a bend diameter of 0.5 inch with no degradation in the optical performance. Finally, we experimentally characterize polarization-rotation effects induced by bending the flexible photonic chips. This work will enable the field of integrated photonics to advance into new application areas that require flexible photonic chips.

Control over the amplitude, phase, and spatial distribution of visible-spectrum light underlies many technologies, but commercial solutions remain bulky, require high control power, and are often too slow. Active integrated photonics for visible light promises a solution, especially with recent materials and fabrication advances. In this review, we discuss three growing application spaces which rely on control of visible light: control and measurement of atomic quantum technologies, augmented-reality displays, and measurement and control of biological systems. We then review the commercial dynamic surfaces and bulk systems which currently provide visible-light modulation and the current state-of-the-art integrated solutions. Throughout the review we focus on speed, control power, size, optical bandwidth, and technological maturity when comparing technologies.

Integrated optical phased arrays (OPAs), fabricated in advanced silicon-photonics platforms, enable manipulation and dynamic control of free-space light in a compact form factor, at low costs, and in a non-mechanical way. In this talk, I will highlight our work on developing OPA-based platforms, devices, and systems that enable chip-based solutions to high-impact problems in areas including augmented-reality displays, LiDAR sensing for autonomous vehicles, optical trapping for biophotonics, 3D printing, and trapped-ion quantum engineering.

In this work, we design and experimentally demonstrate the first, to the best of our knowledge, integrated polarization splitters and rotators at blue wavelengths. We develop compact and efficient designs for both a polarization splitter and rotator at a 422-nm wavelength, an important laser-cooling transition for 88 Sr + ions. These devices are fabricated in a 200-mm wafer-scale process and experimentally demonstrated, resulting in a measured polarization-splitter transverse-electric thru-port coupling of 98.0% and transverse-magnetic tap-port coupling of 77.6% for a compact 16-µm-long device and a polarization-rotator conversion efficiency of 92.2% for a separate compact 111-µm-long device. This work paves the way for more sophisticated integrated control of trapped-ion and neutral-atom quantum systems.

In this Letter, we propose and experimentally demonstrate the first, to our knowledge, integrated liquid-crystal-based (LC-based) variable-tap devices for visible-light amplitude modulation. These devices leverage the birefringence of LC medium to actively tune the coupling coefficient between two waveguides. First, we develop the device structure, theory of operation, and design procedure. Next, we summarize the fabrication and LC packaging procedure for these devices. Finally, we experimentally demonstrate amplitude modulation with 15.4-dB tap-port extinction within ±3.1 V for a 14-µm-long device at a 637-nm operating wavelength. These small-form-factor variable-tap devices provide a compact and low-power solution to integrated visible-light amplitude modulation and will enable future high-density integrated visible-light systems.

A high-resolution 64-channel arrayed-waveguide-grating-assisted silicon-nitride integrated optical phase array is demonstrated for 2-D beam steering. A field of view of 5° ×25° with 0.3° vertical resolution is achieved over a wavelength range of 100 nm with a single optical input. Higher vertical resolution can be attained by utilizing all the inputs of the OPA.

This talk reviews photonic integrated circuit materials, devices and integration techniques developed at MIT Lincoln Laboratory to support the needs of next generation quantum systems across the wavelength spectrum from the near-ultraviolet to the midwave-infrared.

We discuss fabrication processes, important considerations, and evaluation techniques for successful packaging of liquid crystal (LC) into silicon-photonics platforms, enabling compact and power-efficient integrated modulators. We demonstrate an LC-packaging fabrication process, microscopy-based LC-alignment evaluation techniques, a heat-based LC-realignment procedure, and UV-exposure effects on modulator performance.

Underwater wireless optical communications using integrated optical phased arrays is demonstrated for the first time, enabling chip-scale visible-light beamforming for submersible communications. We demonstrate a 1-Gbps on-off-keying link and an electronically-switchable point-to-multipoint link through water.