Large-Scale and Broadband Silicon Nitride Optical Phased Arrays

• Published in: IEEE journal of selected topics in quantum electronics 2022-11, Vol.28 (6: High Density Integr. Multipurpose Photon. Circ.), p.1-10
• Main Authors: Sun, Caiming, Li, Binghui, Shi, Wu, Lin, Jing, Ding, Ning, Tsang, Hon Ki, Zhang, Aidong
• Format: Article
• Language: English
• Subjects: Antenna arrays; Antennas; Apertures; Arrayed waveguide gratings; Beam steering; Broadband; Far fields; grating coupler; Gratings; Laser beams; Optical phased array; Optical waveguides; Phased arrays; Silicon nitride; silicon nitride integrated photonics; silicon photonics; Tuning; Waveguide antennas; Wavelengths
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2022.3182306

Large-scale one-dimensional (1D) waveguide surface grating arrays enable smaller antenna pitches and larger apertures for the OPAs. However, broad wavelength tuning is required for wide-angle beam steering along the transverse θ direction for 1D waveguide antennas. High-resolution and wide-angle beam steerings at visible and NIR wavelengths have not been reported in previous studies. This study presents a large-scale SiNx nanophotonic phased array with an optical aperture of 2.3 mm × 2.3 mm, which is the largest OPA aperture produced in the visible and NIR bands thus far. Broad wavelength tuning from 650 nm to 1064 nm is employed to achieve small beam divergences of 0.03° - 0.054° in a wide steering range of 53.7°. The overall losses are accordingly analyzed with 3 dB bandwidth of 150 nm from 785 nm to 935 nm. Furthermore, with a supercontinuum laser illuminated on the OPA, more than 1000 resolvable spots merge together in the free space and form a fine strip of continuous line in the far-field projection with an FOV of >50°. This study demonstrates both high steering resolution and wide steering angle at wavelengths from visible to NIR on SiNx OPAs for the first time, to the best of our knowledge.