Packaging Considerations and Evaluation Techniques for Integrated Liquid-Crystal-Based Modulators

In this work, we discuss fabrication processes, important considerations, and evaluation techniques for successful packaging of liquid crystal (LC) into silicon-photonics platforms to enable compact and power-efficient integrated LC-based modulators. First, we describe our 300-mm-wafer silicon-photonics foundry fabrication platform and chip-scale LC-packaging process. Second, we demonstrate packaging evaluation techniques for analyzing LC misalignment using both standard and polarizing microscopes. Third, we develop and validate a heat-based procedure to improve packaged LC alignment. Fourth, we study the effect of heat cycling on the integrity of integrated LC-based modulators, showing no significant performance degradation even after 1000 cycles. Finally, we demonstrate the detrimental effects of UV exposure on integrated LC-based modulator performance. This work provides essential insights to facilitate the higher-yield integration and widespread use of integrated LC-based modulators for high-density integrated systems that require compact and power-efficient modulators.