Two-dimensional beam scanning of passive optical phased array based on silicon nitride delay line

Optical phased array has become a potentially critical component for beam scanner benefiting from its advantages in cost, mass production, integration, stability and scanning rate. However, the practicalization of OPA still has some great challenges, such as complex circuit control and the need for pre-calibrated phase. In this paper, we propose two passive OPA chips based on silicon nitride delay lines, which can achieve two-dimensional scanning only by wavelength tuning. The two passive OPA chips have different delay line lengths between 128 channels, achieving 2D scanning efficiency of 0.44°/nm×0.07°/nm and 0.87°/nm×0.07°/nm. The beam quality of both passive OPA chips is excellent, with a side lobe level of about 12 dB, without any degradation compared to the OPA chip without the delay line. The delay length of the proposed passive OPA chip can be further increased to obtain denser 2D scans, thereby improving the practicality of the OPA chip.