Nonvolatile Liquid Controlled Adiabatic Silicon Photonics Switch

A broadband and nonvolatile liquid controlled silicon photonics switch is designed and fabricated. The switch consists of an adiabatic coupler where the oxide above one of the waveguides is removed. Switching is realized by exposing this waveguide to liquids with different refractive indices. The switch design is based on self-consistent orthogonal coupled-mode theory. The measured crosstalk of a 1.4-mm-long switch is less than -38 dB and -11 dB over a 100-nm wavelength range for bar and cross state, respectively. The insertion loss is less than 1 dB. Also the influence of the silicon waveguide thickness and the difference in liquid refractive indices on the switch performance is studied. Furthermore, an improved performance in cross state is demonstrated when a switch is actuated by a gas and a liquid. With a gas-liquid system a very large difference in cladding refractive index can be obtained.