Demonstration of beam steering using a passive silica optical phased array with wavelength tuning

We demonstrate beam steering using a passive silica optical phased array (OPA) with wavelength tuning. In this OPA, a constant path difference is built up to assign sequential phase delays with a wavelength variation in arrayed wave -guide channels for the beam steering. From as-fabricated 1 x 101 passive silica OPA chips, we successfully achieved beam forming with a transversal divergence angle of 0.57 degrees at a 1548.3-nm wavelength and also beam steering of 15.4 degrees by wavelength tuning of 30.7 nm. Combining a cylindri-cal lens in front of the end-fire radiators, the longitudinal divergence angle could be reduced from 13.0 degrees to 0.42 degrees. The side-mode suppression ratio of the beam was 10.3 dB at the center position. Through simulation, we analyzed the effects of the phase errors on the beam quality, due to the effective index fluctuation of the waveguide channels, and provided an allowable error range to attain beam forming from the passive OPA.(c) 2022 Optica Publishing Group