Mechanical-Contact-Based Submicron-Si-Waveguide Optical Microswitch at Telecommunication Wavelengths

We report a mechanical-contact-based single-input single-output normally-closed optical microswitch. The switch comprises an input and an identical output waveguide, and a movable low-loss elliptical waveguide driven by a miniature electrostatic comb drive. Movable waveguide closes the lateral gap between input and output waveguides. Mechanical contact of waveguide tip surfaces enables light propagation from the input to the output waveguide through movable elliptical waveguide. Optical property of the switch is studied by finite difference time domain (FDTD) analysis. An SOI wafer with 260 nm-thick device-Si and 2 mum-thick buried-oxide layers is utilized in the fabrication. TE-polarized near infrared light at 1.55 mum wavelength is coupled into the input waveguide through an IR objective lens in free-space, and switch is observed with the help of a vidicon camera. Approximately 30plusmn2 dB switching contrast is obtained experimentally at 540 nm lateral switch motion between on and off states.