Hitless two-dimensional focal plane switch array based on Mach-Zehnder interferometer-embedded micro-ring resonators

Empowered by compact micro-ring (MRR) arrays, wavelength-division-multiplexing (WDM)-based focal plane switch array (FPSA) chip is a promising solution for light detection and ranging (LiDAR) due to its parallelism and high-level integration. However, an MRR channel with a shifting central wavelength may interrupt another channel by dropping an optical signal with an unexpected wavelength, which causes discontinuous beam scanning. To overcome this bottleneck, we propose and fabricate a hitless two-dimensional (2-D) FPSA chip based on a 2 × 8 Mach-Zehnder interferometer-embedded micro-ring resonator (MZER) array. The FPSA chip realizes a beam divergence of 0.18° × 0.05°, a field of view (FoV) of 9.07° × 6.42° with single-ended emission, and a FoV of 10.75° × 6.42° with dual-ended field-of-view splicing technology. Besides, we demonstrate the hitless function of our FPSA chip by performing continuous wavelength sweeping and further applying it to a free-space optical communication link. The experimental results validate the feasibility of our proposed hitless FPSA chip, which efficiently prevents signal interruptions during beam steering.