Woosung Kim

Bio: Woosung Kim is an academic researcher from Intel. The author has contributed to research in topics: Optical isolator & Photonic integrated circuit. The author has an hindex of 2, co-authored 5 publications receiving 272 citations.

High-resolution aliasing-free optical beam steering

Abstract: Many applications, including laser (LIDAR) mapping, free-space optical communications, and spatially resolved optical sensors, demand compact, robust solutions to steering an optical beam. Fine target addressability (high steering resolution) in these systems requires simultaneously achieving a wide steering angle and a small beam divergence, but this is difficult due to the fundamental trade-offs between resolution and steering range. So far, to our knowledge, chip-based two-axis optical phased arrays have achieved a resolution of no more than 23 resolvable spots in the phased-array axis. Here we report, using non-uniform emitter spacing on a large-scale emitter array, a dramatically higher-performance two-axis steerable optical phased array fabricated in a 300 mm CMOS facility with over 500 resolvable spots and 80° steering in the phased-array axis (measurement limited) and a record small divergence in both axes (0.14°). Including the demonstrated steering range in the other (wavelength-controlled) axis, this amounts to two-dimensional beam steering to more than 60,000 resolvable points.

On-chip optical isolator

Abstract: Embodiments herein relate to photonic integrated circuits with an on-chip optical isolator. A photonic transmitter chip may include a laser and an on-chip isolator optically coupled with the laser that includes an optical waveguide having a section coupled with a magneto-optic liquid phase epitaxy grown garnet film. In some embodiments, a cladding may be coupled with the garnet film, the on-chip isolator may be arranged in a Mach-Zehnder interferometer configuration, the waveguide may include one or more polarization rotators, and/or the garnet film may be formed of a material from a rare-earth garnet family. Other embodiments may be described and/or claimed.

Optical iso-modulator

Abstract: Apparatuses, methods and storage medium associated with an optical iso-modulator are disclosed herein. In embodiments, an apparatus may include an optical waveguide formed on one or more layers, such as an isolation layer and a handling layer. A modulator driver may be coupled to a first side of the one or more layers. A magneto-optical (MO) die may be coupled to a second side of the one or more layers that is opposite the first side. Other embodiments may be disclosed and/or claimed.

Feedback controlled closed loop on-chip isolator

Abstract: Embodiments herein relate to a photonic integrated circuit (PIC) with an on-chip optical isolator. The PIC may comprise a laser, a waveguide coupled with the laser, and a closed loop resonator coupled to the laser through the waveguide. A magneto-optical (MO) layer is over and in contact with the waveguide and the closed loop resonator. The closed loop resonator may comprise a first polarization rotator (PR) and a second PR. A light from the laser in transverse electric (TE) mode through the waveguide is rotated in the first PR to a light in transverse magnetic (TM) mode, and the light in TM mode is rotated in the second PR to light in TE mode. The isolator may further comprise a micro-heater over or along a side of the waveguide and separated from the closed loop resonator; and a feedback control loop connected to the closed loop resonator and the micro-heater.

Optical modulator-based transmission control

Abstract: Embodiments may relate to an optical modulator system. The optical modulator system may include a first photodiode to measure a first optical level at an output of a Mach-Zehnder modulator (MZM). The system may further include a second photodiode to measure a second optical level at a termination of the MZM. The system may further include a logic coupled with the first photodiode and the second photodiode, the logic to identify a modulator bias that minimizes the first optical level. Other embodiments may be described or claimed.

Coherent solid-state LIDAR with silicon photonic optical phased arrays

Abstract: We present, to the best of our knowledge, the first demonstration of coherent solid-state light detection and ranging (LIDAR) using optical phased arrays in a silicon photonics platform. An integrated transmitting and receiving frequency-modulated continuous-wave circuit was initially developed and tested to confirm on-chip ranging. Simultaneous distance and velocity measurements were performed using triangular frequency modulation. Transmitting and receiving optical phased arrays were added to the system for on-chip beam collimation, and solid-state beam steering and ranging measurements using this system are shown. A cascaded optical phase shifter architecture with multiple groups was used to simplify system control and allow for a compact packaged device. This system was fabricated within a 300 mm wafer CMOS-compatible platform and paves the way for disruptive low-cost and compact LIDAR on-chip technology.

Long-Range LiDAR and Free-Space Data Communication With High-Performance Optical Phased Arrays

Abstract: We present high-performance integrated optical phased arrays along with first-of-their-kind light detection and ranging (LiDAR) and free-space data communication demonstrators. First, record-performance optical phased array components are shown with low-power phase shifters and high-directionality waveguide grating antennas. Then, one-dimensional (1-D) 512-element optical phased arrays are demonstrated with record low-power operation ( $ 1 mW total), large steering ranges, and high-speed two-dimensional (2-D) beam steering ( $ 30 $\mu$ s phase shifter time constant). Next, by utilizing optical phased arrays, we show coherent 2-D solid-state LiDAR on diffusive targets with simultaneous velocity extraction at a range of nearly 200 m. In addition, the first demonstration of 3-D coherent LiDAR with optical phased arrays is presented with raster-scanning arrays. Finally, lens-free chip-to-chip free-space optical communication links up to 50 m are shown, including a demonstration of a steerable transmitter to multiple optical phased array receivers at a 1 Gb/s data rate. This paper shows the most advanced silicon photonics solid-state beam steering to date with relevant demonstrators in practical applications.

Large-scale silicon nitride nanophotonic phased arrays at infrared and visible wavelengths.

Abstract: We demonstrate passive large-scale nanophotonic phased arrays in a CMOS-compatible silicon photonic platform. Silicon nitride waveguides are used to allow for higher input power and lower phase variation compared to a silicon-based distribution network. A phased array at an infrared wavelength of 1550 nm is demonstrated with an ultra-large aperture size of 4 mm×4 mm, achieving a record small and near diffraction-limited spot size of 0.021°×0.021° with a side lobe suppression of 10 dB. A main beam power of 400 mW is observed. Using the same silicon nitride platform and phased array architecture, we also demonstrate, to the best of our knowledge, the first large-aperture visible nanophotonic phased array at 635 nm with an aperture size of 0.5 mm×0.5 mm and a spot size of 0.064°×0.074°.

A Monolithically Integrated Large-Scale Optical Phased Array in Silicon-on-Insulator CMOS

Abstract: A large-scale monolithic silicon nanophotonic phased array on a chip creates and dynamically steers a high-resolution optical beam in free space, enabling emerging applications in sensing, imaging, and communication. The scalable architecture leverages sub-array structure, mitigating the impact of process variation on the phased array performance. In addition, sharing control electronics among multiple optical modulators in the scalable architecture reduces the number of digital-to-analog converters (DACs) required for an $N^{2}$ array from $\mathcal {O}(N^{2})$ to $\mathcal {O}(N)$ , allowing a small silicon footprint. An optical phased array for 1550-nm wavelength with 1024 uniformly spaced optical grating antennas, 1192 optical variable phase shifters, and 168 optical variable attenuators is integrated into a 5.7 mm $\times$ 6.4 mm chip in a commercial 180-nm silicon-on-insulator RF CMOS technology. The control signals for the optical variable phase shifters and attenuators are provided by 136 DACs with 14-bit nonuniform resolution using 2.5-V input-output transistors. The implemented phased array can create 0.03° narrow optical beams that can be steered unambiguously within ±22.5°.

Large-scale optical phased array using a low-power multi-pass silicon photonic platform

Abstract: Optical phased arrays are a promising beam-steering technology for ultra-small solid-state lidar and free-space communication systems. Long-range, high-performance arrays require a large beam emission area densely packed with thousands of actively phase-controlled, power-hungry light emitting elements. To date, such large-scale phased arrays have been impossible to realize since current demonstrated technologies would operate at untenable electrical power levels. Here we show a multi-pass photonic platform integrated into a large-scale phased array that lowers phase shifter power consumption by nearly 9 times. The multi-pass structure decreases the power consumption of a thermo-optic phase shifter to a ${{\rm P}_\pi }$Pπ of ${1.7}\;{\rm mW/}\pi $1.7mW/π without sacrificing speed or optical bandwidth. Using this platform, we demonstrate a silicon photonic phased array containing 512 actively controlled elements, consuming only 1.9 W of power while performing 2D beam steering over a ${70}^\circ \times {6}^\circ $70∘×6∘ field of view. Our results demonstrate a path forward to building scalable phased arrays containing thousands of active elements.