Integrated visible-light liquid-crystal-based phase modulators

In this work, an integrated liquid-crystal-based phase modulator operating at visible wavelengths was developed and experimentally demonstrated. A visible-light silicon-nitride-based 300-mm-wafer foundry platform and a liquid-crystal integration process were developed to leverage the birefringence of liquid crystal to actively tune the effective index of a section of silicon-nitride waveguide and induce a phase shift over its length. The device was experimentally shown to achieve a 41 pi phase shift within 4.8 V-pp for a 500-mu m-long modulator, which means that a 2 pi phase shifter would need to be only 24.4 mu m long. This device is a compact and low-power solution to the challenge of integrated phase modulation in silicon nitride and paves the way for future low-power small-form-factor integrated systems at visible wavelengths. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement