Three-wavelengths integrated SiN optical phased array for LiDAR and FSO data link applications

Abstract

We propose a scalable integrated silicon nitride optical phased array (OPA) enabling multi-beam emission and two-dimensional continuous beam steering for light detection and ranging (LiDAR), free-space optics (FSO), and data link applications. The emitters are optimized grating couplers for wavelengths of 800 nm, 850 nm, and 905 nm. We propose three OPAs, two with 8 emitters and one with 16 emitters. The OPAs are characterized at a wavelength of 850nm. The measured beam size of the OPAs are 0.96° ×0.12°, 0.69° ×5.42°, and 0.7° ×1.53°. A lateral beam steering of ±12.35° is measured. The proposed configuration of the thermo-optical phase shifters along the OPA tree provides a simple multi-level beam splitting resolution for each OPA. By enhancing the unwanted side lobes, a discrete angular selection resolution is achieved, improving from 6.1° to 0.082°. We proposed an array of heaters to suppress the unwanted side lobes of the radiation pattern, and its performance is measured and presented. We measured the modulated beam considering pulses with different duty cycles up to 5 MHz and data rates up to 6.25 Mb/s.