Voltage-Driven Near Field Beam Shifting in an InP Photonic Integrated Circuit

A voltage-driven, continuously-tuned beam shifting device is proposed, simulated, and demonstrated in an InP photonic integrated circuit. Electrodes are applied on the left and right side of a mode-expanded waveguide to electronically control the refractive index profile and shift the optical beam by means of reverse bias voltage. The feasibility of a beam shifting of 4.9 μm with a power consumption of the order of 4.5 pW and voltage of 10 V is numerically predicted for a beam shifting element with ideal electrical isolation and fundamental input mode excitation. The reduction in beam-shifting efficiency is subsequently quantified for imperfect electrical isolation and in the presence of higher order mode excitation at the input to the beam shifting element. An experimental proof of concept is implemented by realizing the device on a generic photonic integration platform and co-integrating an on-chip tunable laser. High-resolution near-field measurements show near-field beam shifting of 1 μm with an applied voltage range from -4 to 0 V.