Wide-steering-angle high-resolution optical phased array

Optical phased array (OPA) technology is considered a promising solution for solid-state beam steering to supersede the traditional mechanical beam steering. As a key component of the LIDAR system for long-range detection, OPAs featuring a wide steering angle and high resolution without beam aliasing are highly desired. However, a wide steering range requires a waveguide pitch less than half of the wavelength, which is easily subjected to cross talk. Besides, high resolution requires a large aperture, and it is normally achieved by a high count number of waveguides, which complicates the control system. To solve the mentioned issues, we design two high-performance 128-channel OPAs fabricated on a multilayered SiN-on-SOI platform. Attributed to the nonuniform antenna pitch, only 128 waveguides are used to achieve a 4 mm wide aperture. Besides, by virtue of innovative dual-level silicon nitride (Si3N4) waveguide grating antennas, the fishbone antenna OPA achieves a 100 degrees x 19.4 degrees field of view (FOV) with divergence of 0.021 degrees x 0.029 degrees, and the chain antenna OPA realizes a 140 degrees x 19.23 degrees FOV with divergence of 0.021 degrees x 0.1 degrees. To our best knowledge, 140 degrees is the widest lateral steering range in two-dimensional OPA, and 0.029 degrees is the smallest longitudinal divergence. Finally, we embed the OPA into a frequency-modulated continuous-wave system to achieve 100 m distance measurement. The reflected signal from 100 m distance is well detected with 26 dBm input transmitter power, which proves that OPA serves as a promising candidate for transceiving optical signal in a LIDAR system. (C) 2021 Chinese Laser Press

Automated summary

Optical phased array (OPA) technology is seen as a promising solution for solid-state beam steering, but faces challenges such as cross talk and complexity in control systems. To address these issues, we designed high-performance OPAs with a wide steering angle and high resolution on a multilayered SiN-on-SOI platform, achieving a large aperture with a relatively low count of waveguides.