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We consider the impact of intra-wafer systematic spatial variation, pattern density mismatch, and line edge roughness on splitter-tree-based integrated optical phased arrays. These variations can substantially affect the emitted beam profile in the array dimension. We study the effect on different architecture parameters, and the analysis is shown to be consistent with experimental results.

In this work, an integrated liquid-crystal-based phase modulator operating at visible wavelengths was developed and experimentally demonstrated. A visible-light silicon-nitride-based 300-mm-wafer foundry platform and a liquid-crystal integration process were developed to leverage the birefringence of liquid crystal to actively tune the effective index of a section of silicon-nitride waveguide and induce a phase shift over its length. The device was experimentally shown to achieve a 41π phase shift within 4.8 Vpp for a 500-µm-long modulator, which means that a 2π phase shifter would need to be only 24.4 µm long. This device is a compact and low-power solution to the challenge of integrated phase modulation in silicon nitride and paves the way for future low-power small-form-factor integrated systems at visible wavelengths.

We develop a wafer-scale CMOS-compatible platform and fabrication process that results in 300-mm-diameter flexible wafers, and experimentally demonstrate key functionality at visible wavelengths, including chip coupling, waveguide routing, and passive devices.

We develop a framework for two advanced trapped-ion cooling schemes, polarization-gradient and electromagnetically-induced-transparency cooling, for 88Sr+ ions using a visible-wavelength integrated-photonics platform and present the design of the key integrated devices.

Optical trapping using integrated optical phased arrays is demonstrated, enabling chip-based trapping at distances compatible with standard biological experimentation and opening the door to broader implementation of optical-trapping technology.

This work introduces an integrated photonic system that enables curing of a visible-light-curable resin for chip-based 3D printing. Curing of multiple mm-scale regions is achieved via an integrated optical phased array operating at 632.8 nm.

Recent integrated optical phased array architectures, results, and applications will be reviewed, including beam steering for LiDAR, near-field optical manipulation, and holographic displays for augmented reality.

Integrated polarization rotators and splitters are designed for the first time at visible wavelengths. Specifically, an adiabatic polarization rotator, an off-axis polarization rotator, and a mode-coupling polarization splitter are designed in a silicon-nitride platform.

An advanced CMOS-compatible 300- $\text{mm}$ -wafer silicon-photonics platform is introduced that consists of a silicon layer with eight doping masks, two silicon-nitride layers, three metal and via layers, a dicing trench for smooth edge-coupled facets, and a gain-film trench that enables interaction between the gain material and waveguide layers. The platform was used to demonstrate an electrically-steerable integrated optical phased array powered by an on-chip erbium-doped laser. Lasing with a single-mode output, $30\,\text{dB}$ side-mode-suppression ratio, and $\text{40 mW}$ lasing threshold was shown, and one-dimensional beam steering with a $\text{0.85}^\circ \times \text{0.20}^\circ$ full-width at half-maximum and $\text{30}^\circ /\text{W}$ electrical steering efficiency was demonstrated. This system represents the first demonstration of a rare-earth-doped laser monolithically-integrated with an active CMOS-compatible silicon-on-insulator photonics system.

With the growing demand for automotive LiDAR and the maturation of silicon photonics platforms, optical phased arrays (OPAs) have emerged as a key technology for solid-state optical beam-steering. In order to meet realistic automotive specifications with OPAs, >500 antenna elements should work reliably under tight power and cost budgets. Existing multi-chip solutions necessitate expensive packaging and assembly to achieve high interconnect density. Even with 2-D monolithic integration, high-voltage drivers to deliver sufficient power to resistive phase shifters typically result in significant overhead in die area and limited power efficiency. In this article, we introduce a single-chip OPA realized through wafer-scale 3-D integration of silicon photonics and CMOS. Flexible and ultra-dense connections with through-oxide vias (TOVs) in our platform resolve the I/O density issue. Moreover, low-voltage L-shaped phase shifters and compact, efficient switch-mode drivers, connected vertically using TOVs, remove wiring/placement overhead and achieve a large active array aperture within a compact die. Our OPA prototype achieves wide-range 2-D steering over 18.5 $^\circ \times $ 16° by leveraging wavelength tuning and phase control, and array scaling up to 125 elements with a large aperture size of $0.5\,\mathrm {mm}\times 0.5\,\mathrm {mm}$ and 0.15 $^\circ \times $ 0.25° beamwidth while consuming 20 mW/element average power. Since our system supports per-element independent phase control, increased sensitivity to process variations in L-shaped shifters is fully compensated by a simple calibration process.

Integrated optical phased arrays that focus radiated light to a tightly-confined spot in the near field are demonstrated for the first time. The element phase distributions necessary for generating and steering focused beams using phased arrays are developed. Discussion and simulations detailing the effects of the array aperture and focal length on the focal spot are included. Two focusing phased array architectures are presented: (1) a one-dimensional splitter-tree-based architecture with novel focusing antennas and inline phase bumps and (2) a two-dimensional large-scale pixel-based architecture. Both architectures are used to experimentally demonstrate a variety of aperture size and focal length passive focusing arrays in a CMOS-compatible platform, including (i) a 512-antenna splitter-tree-based array with a wavelength-steerable 7 µm spot at a 5 mm focal length, (ii) a 1024-antenna pixel-based array with a 21 µm spot at a 5 mm focal length, and (iii) a 10,000-antenna pixel-based array with a 21 µm spot at a 10 mm focal length. The demonstrated focusing phased arrays present a new functional modality compared to standard optical phased arrays that generate diffracting beams in the far field of the array. This new focusing modality has the potential to advance a number of important application areas at the cutting edge of lightwave technology, as it will enable future integrated optical phased array implementations for a wide range of applications that require focusing operation. Such areas include optical trapping for biological characterization, laser-based three-dimensional printing, short-range light detection and ranging, and short-range optical data communications.

We demonstrate DC-Kerr-effect-based modulation at a temperature of 5 K at GHz speeds in silicon photonic phase shifters fabricated in a CMOS-compatible process. The cryogenic performance of the devices remains comparable to that at room temperature.

Recent integrated optical phased array architectures, results, and applications will be reviewed, including beam steering for LiDAR and communications, near-field optical manipulation, and holographic displays for augmented reality.

The accuracy of conventional ADCs for high-frequency input signals is mainly limited by the sampling clock jitter. To address this issue, this paper demonstrates an ADC that uses low-jitter $( optical pulses to sample the input signal. A prototype two-channel ADC is realized in a 3D integrated platform with 65 nm CMOS and silicon-photonics connected using high-density TOVs. With optical pulses spaced at 250 ps (4 GS/s effective sampling rate), the ADC achieves SNDR of 40 dB near DC and 37 dB at 45 GHz input.

Recent integrated optical phased array architectures, results, and applications will be reviewed. Beam-steering optical phased arrays monolithically integrated with on-chip rare-earth-doped lasers and heterogeneously integrated with CMOS driving electronics will be shown. Passive integrated optical phased arrays that focus radiated light to tightly-confined spots in the near field and that generate quasi-Bessel beams will be discussed. Finally, integrated-phased-array-based visible-light holographic displays will be proposed as a scalable solution towards the next generation of augmented-reality head-mounted displays; passive near-eye holographic displays, visible-light liquid-crystal modulators, and liquid-crystal-based visible-light phased arrays will be presented.

Scientific reports 10(1), 1114 (1-9) (2020). doi:10.1038/s41598-020-57928-5, To meet the increasing demand for data communication bandwidth and overcome the limits of electrical interconnects, silicon photonic technology has been extensively studied, with various photonics devices and optical links being demonstrated. All of the optical data links previously demonstrated have used either heterogeneously integrated lasers or external laser sources. This work presents the first silicon photonic data link using a monolithic rare-earth-ion-doped laser, a silicon microdisk modulator, and a germanium photodetector integrated on a single chip. The fabrication is CMOS compatible, demonstrating data transmission as a proof-of-concept at kHz speed level, and potential data rate of more than 1Gbps. This work provides a solution for the monolithic integration of laser sources on the silicon photonic platform, which is fully compatible with the CMOS fabrication line, and has potential applications such as free-space communication and integrated LIDAR., Published by Macmillan Publishers Limited, part of Springer Nature, [London]

Reliable operation of photonic integrated circuits at cryogenic temperatures would enable new capabilities for emerging computing platforms, such as quantum technologies and low-power cryogenic computing. The silicon-on-insulator platform is a highly promising approach to developing large-scale photonic integrated circuits due to its exceptional manufacturability, CMOS compatibility, and high component density. Fast, efficient, and low-loss modulation at cryogenic temperatures in silicon, however, remains an outstanding challenge, particularly without the addition of exotic nonlinear optical materials. In this paper, we demonstrate DC-Kerr-effect-based modulation at a temperature of 5 K at GHz speeds, in a silicon photonic device fabricated exclusively within a CMOS-compatible process. This work opens up a path for the integration of DC Kerr modulators in large-scale photonic integrated circuits for emerging cryogenic classical and quantum computing applications.

Recent integrated optical phased array architectures, results, and applications will be reviewed, including beam steering for LiDAR and communications, near-field optical manipulation, and holographic displays for augmented reality.

Recent integrated optical phased array architectures, results, and applications will be reviewed. Monolithic integration with lasers, near-field focusing, quasi-Bessel-beam generation, and visible-light holographic projection will be discussed.

The realization of a low-cost and robust optical beam-steering platform is a key enabler for a number of applications, including light detection and ranging (LIDAR) and free-space optical communications (FSO). Optical phased arrays (OPAs) have emerged as a promising solution, due to advancements in photonic integrated circuits (PIC) foundry processes, which have enabled high-precision fabrication of PICs with a large number of components [1]–[3]. In order to meet steering range and directivity requirements in systems such as autonomous vehicles, a clear path to scaling OPAs to millimeter-scale apertures with thousands of tight-pitched antenna elements is critical. As the element count grows, independent phase control for each element becomes crucial since maintaining coherence between elements becomes more difficult due to process variations. Moreover, independent control allows for unique system capabilities, such as multi-beam formation and converging/adaptive beams, which makes OPAs a particularly attractive solid-state beamforming technology.

Light 8, 122 (2019)., Optical frequency synthesizers have widespread applications in optical spectroscopy, frequency metrology, and many other fields. However, their applicability is currently limited by size, cost, and power consumption. Silicon photonics technology, which is compatible with complementary-metal-oxide-semiconductor fabrication processes, provides a low-cost, compact size, lightweight, and low-power-consumption solution. In this work, we demonstrate an optical frequency synthesizer using a fully integrated silicon-based tunable laser. The synthesizer can be self-calibrated by tuning the repetition rate of the internal mode-locked laser. A 20 nm tuning range from 1544 to 1564 nm is achieved with ~10−13 frequency instability at 10 s averaging time. Its flexibility and fast reconfigurability are also demonstrated by fine tuning the synthesizer and generating arbitrary specified patterns over time-frequency coordinates. This work promotes the frequency stability of silicon-based integrated tunable lasers and paves the way toward chip-scale low-cost optical frequency synthesizers., Published by Nature Publishing Group, London

Silicon Photonics: From Fundamental Research to Manufacturing : [Proceedings] - SPIE, 2018. - ISBN 97815106189859781510618992 - doi:10.1117/12.2318010 Silicon Photonics: from Fundamental Research to Manufacturing, SPIE.Photonics Europe, Strasbourg, France, 22 Apr 2018 - 26 Apr 2018; SPIE, 11 pp. (2018). doi:10.1117/12.2318010, Mode-locked lasers provide extremely low jitter optical pulse trains for a number of applications ranging from sampling of RF-signals and optical frequency combs to microwave and optical signal synthesis. Integrated versions have the advantage of high reliability, low cost and compact. Here, we describe a fully integrated mode-locked laser architectureon a CMOS platform that utilizes rare-earth doped gain media, double-chirped waveguide gratings for dispersion compensation and nonlinear Michelson Interferometers for generating an artificial saturable absorber to implement additive pulse mode locking on chip. First results of devices at 1.9 µm using thulium doped aluminum-oxide glass and operating in the Q-switched mode locking regime are presented., Published by SPIE

An integrated liquid-crystal phase modulator for applications within the visible wavelength range is demonstrated. A threshold voltage of ±1.2V is shown and 24π phase shift is achieved within ±2.5V in a 500-μm-long modulator.

A tunable laser source is a crucial photonic component for many applications, such as spectroscopic measurements, wavelength division multiplexing (WDM), frequency-modulated light detection and ranging (LIDAR), and optical coherence tomography (OCT). In this article, we demonstrate the first monolithically integrated erbium-doped tunable laser on a complementary-metal-oxide-semiconductor (CMOS)-compatible silicon photonics platform. Erbium-doped Al2O3 sputtered on top is used as a gain medium to achieve lasing. The laser achieves a tunability from 1527 nm to 1573 nm, with a >40 dB side mode suppression ratio (SMSR). The wide tuning range (46 nm) is realized with a Vernier cavity, formed by two Si3N4 microring resonators. With 107 mW on-chip 980 nm pump power, up to 1.6 mW output lasing power is obtained with a 2.2% slope efficiency. The maximum output power is limited by pump power. Fine tuning of the laser wavelength is demonstrated by using the gain cavity phase shifter. Signal response times are measured to be around 200 mu s and 35 mu s for the heaters used to tune the Vernier rings and gain cavity longitudinal mode, respectively. The linewidth of the laser is 340 kHz. measured via a self-delay heterodyne detection method. Furthermore, the laser signal is stabilized by continuous locking to a mode-locked laser (MLL) over 4900 seconds with a measured peak-to-peak frequency deviation below 10 Hz., Defense Advanced Research Projects Agency (DARPA) Direct On-Chip Digital Optical Synthesizer (DODOS) project

Generation of Bessel beams using integrated optical phased arrays is proposed and experimentally demonstrated for the first time. A quasi-Bessel beam with a ∼14mm Bessel length and ∼30 μm FWHM is generated using a splitter-tree-based architecture.

We present the integration of optical passive and active components next to millions of nano-scale bulk silicon transistors through a single deposited layer of polysilicon on silicon oxide islands. We demonstrate 10 Gb/s monolithic O-band optical transceivers on this platform.

Electronic and photonic technologies have transformed our lives-from computing and mobile devices, to information technology and the internet. Our future demands in these fields require innovation in each technology separately, but also depend on our ability to harness their complementary physics through integrated solutions1,2. This goal is hindered by the fact that most silicon nanotechnologies-which enable our processors, computer memory, communications chips and image sensors-rely on bulk silicon substrates, a cost-effective solution with an abundant supply chain, but with substantial limitations for the integration of photonic functions. Here we introduce photonics into bulk silicon complementary metal-oxide-semiconductor (CMOS) chips using a layer of polycrystalline silicon deposited on silicon oxide (glass) islands fabricated alongside transistors. We use this single deposited layer to realize optical waveguides and resonators, high-speed optical modulators and sensitive avalanche photodetectors. We integrated this photonic platform with a 65-nanometre-transistor bulk CMOS process technology inside a 300-millimetre-diameter-wafer microelectronics foundry. We then implemented integrated high-speed optical transceivers in this platform that operate at ten gigabits per second, composed of millions of transistors, and arrayed on a single optical bus for wavelength division multiplexing, to address the demand for high-bandwidth optical interconnects in data centres and high-performance computing3,4. By decoupling the formation of photonic devices from that of transistors, this integration approach can achieve many of the goals of multi-chip solutions 5 , but with the performance, complexity and scalability of 'systems on a chip'1,6-8. As transistors smaller than ten nanometres across become commercially available 9 , and as new nanotechnologies emerge10,11, this approach could provide a way to integrate photonics with state-of-the-art nanoelectronics.

Integrated optical phased arrays for generating quasi-Bessel beams are proposed and experimentally demonstrated in a CMOS-compatible platform. Owing to their elongated central beams, Bessel beams have applications in a range of fields, including multiparticle trapping and laser lithography. In this Letter, continuous Bessel theory is manipulated to formulate the phase and amplitude conditions necessary for generating free-space-propagating Bessel–Gauss beams using on-chip optical phased arrays. Discussion of the effects of select phased array parameters on the generated beam’s figures of merit is included. A one-dimensional splitter-tree-based phased array architecture is modified to enable arbitrary passive control of the array’s element phase and amplitude distributions. This architecture is used to experimentally demonstrate on-chip quasi-Bessel-beam generation with a ∼14 mm Bessel length and ∼30 μm power full width at half maximum.

We demonstrate a large-scale tunable-coupling ring resonator array, suitable for high-dimensional classical and quantum transforms, in a CMOS-compatible silicon photonics platform. The device consists of a waveguide coupled to 15 ring-based dispersive elements with programmable linewidths and resonance frequencies. The ability to control both quality factor and frequency of each ring provides an unprecedented 30 degrees of freedom in dispersion control on a single spatial channel. This programmable dispersion control system has a range of applications, including mode-locked lasers, quantum key distribution, and photon-pair generation. We also propose a novel application enabled by this circuit – high-speed quantum communications using temporal-mode-based quantum data locking – and discuss the utility of the system for performing the high-dimensional unitary optical transformations necessary for a quantum data locking demonstration.

An integrated optical phased array which focuses radiated light in one dimension to a tightly confined spot in the near field is demonstrated for the first time and proposed for chip-scale optical trapping applications.

We present poly-silicon depletion-based optical modulators realized in a 65 nm CMOS platform for monolithic integration with electronics. Speeds up to 12.5 Gbit/s can be achieved with 5 dB insertion loss and 2.3 dB extinction ratio.

Apodized bi-level fiber-to-chip grating couplers, designed using a complex-wavevector band-structure approach, are demonstrated in a commercially available, monolithic SOI CMOS process achieving 92% (−0.36dB) coupling efficiency.

A large-scale tunable-coupling ring resonator array is demonstrated in a CMOS-compatible silicon photonics platform to achieve tunable frequency-dependent group delay. The system is proposed for a phase-encoded quantum data locking protocol.

In this Letter, owing to an error during the production process, the author affiliations were listed incorrectly. Affiliation number 5 (Colleges of Nanoscale Science and Engineering, State University of New York (SUNY)) was repeated, and affiliation numbers 6-8 were incorrect. In addition, the phrase "two oxide thickness variants" should have been "two gate oxide thickness variants". These errors have all been corrected online.