Initial alignment control technique using on-chip groove arrays for liquid crystal hybrid silicon optical phase...

Flexible and localized initial alignment control of liquid crystal (LC) is important to enhance the performance and functionality of LC hybrid silicon photonic devices. This work proposes an initial LC alignment control technique based on integration of a nanometer-scale groove array in the buried oxide layer near a Si waveguide. We achieved control of the initial angle of LC director around the Si waveguide by selecting the required integrated groove direction and reduced the driving voltage by introducing a vertical groove array into the phase shifter. We then used the local and flexible LC initial alignment controllability to develop a Mach-Zehnder optical switch and ring-resonator wavelength filter. This approach will be helpful when integrating LC-loaded devices with various characteristics and functionalities into optical integrated circuits.