Temperature Dependence of the Steering Angles of a Silicon Photonic Optical Phased Array

Silicon photonic optical phased arrays leveraging from the well established CMOS fabrication process have become promising candidates to realize miniaturized beam steering systems. While different implementations of optical phased arrays have been successfully demonstrated, no investigations on the influence of thermal distortions on the response of these systems have been performed so far. Due to the high thermo-optic coefficient of silicon, the refractive index and thus the functionality of silicon photonic components depend strongly on the temperature. In highly integrated systems, consisting of several photonic components, in which laser sources and control electronics are directly integrated on top of the photonic IC, heat dissipated by active components leads to temperature gradients and offsets, affecting the functionality of the photonic system. Optical phased arrays consisting of an array of phase sensitive components, are particularly sensitive towards temperature. Therefore, precise investigations of the temperature dependence of the OPA functionality are required. This article aims to expand the understanding of the influence of thermal distortions on the steering angles of optical phased arrays. Thereto, analytical expressions describing the temperature dependence of the steering angles are provided and experimentally validated. The expressions are provided in a general form so that they can be applied to any OPA system regardless of its implementation.