Wide-steering-angle high-resolution optical phased array
Yingzhi Li, Baisong Chen, Quanxin Na, Qijie Xie, Min Tao, Lanxuan Zhang, Zihao Zhi, Yuxuan Li, Xiaobin Liu, Xianshu Luo, Guo‐Qiang Lo, Fengli Gao, Xueyan Li, Junfeng Song
Abstract
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 ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m1"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>Si</mml:mi> </mml:mrow> <mml:mn>3</mml:mn> </mml:msub> <mml:msub> <mml:mi mathvariant="normal">N</mml:mi> <mml:mn>4</mml:mn> </mml:msub> </mml:mrow> </mml:math> ) waveguide grating antennas, the fishbone antenna OPA achieves a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m2"> <mml:mrow> <mml:mn>100</mml:mn> <mml:mo>°</mml:mo> <mml:mo>×</mml:mo> <mml:mn>19.4</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> </mml:math> field of view (FOV) with divergence of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m3"> <mml:mrow> <mml:mn>0.021</mml:mn> <mml:mo>°</mml:mo> <mml:mo>×</mml:mo> <mml:mn>0.029</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> </mml:math> , and the chain antenna OPA realizes a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m4"> <mml:mrow> <mml:mn>140</mml:mn> <mml:mo>°</mml:mo> <mml:mo>×</mml:mo> <mml:mn>19.23</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> </mml:math> FOV with divergence of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="m5"> <mml:mrow> <mml:mn>0.021</mml:mn> <mml:mo>°</mml:mo> <mml:mo>×</mml:mo> <mml:mn>0.1</mml:mn> <mml:mo>°</mml:mo> </mml:mrow> </mml:math> . To our best knowledge, 140° is the widest lateral steering range in two-dimensional OPA, and 0.029° 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.