Lithium Niobate Electro-Optic Phase Shifters for Reconfigurable Beam Steering

Achieving accurate and reliable beam steering in optical phased arrays (OPAs) is strongly dependent on precision of the phase shifts applied between the unit radiators of the OPAs. In this work, we present the design of lithium niobate (LN) optical phase shifters required to drive optical phased arrays for beam steering in on-chip optical wireless switches. Two different configurations for these phase shifters are analyzed by exploiting the electro-optic effect of lithium niobate. In particular, an OPA-based 1×3 on-chip optical wireless switch is considered as a case study, in which a transmitter can address one of the three in-plane receivers through phase tuning. These phase shifts between the antenna elements of the OPA are driven by electro-optic phase shifters. We numerically evaluate the energy needed to induce the desired phase shifts, required for beam steering. Our simulation results show that the optical phase shifters based on the LN rib waveguide are more compact and energy efficient with respect to the ones based on LN strip waveguide. It is found that, in this configuration, the total energy required by the phase shifters to switch optical signals from one receiver to another in the wireless switch is 5.6 pJ.