Tunable air-suspended polymer grating couplers

We present thermal tuning of air-suspended SU-8 polymer waveguide grating couplers for TEpolarized light. Numerical simulations have been performed to estimate the wavelength shift caused by the change of temperature. Due to the small positive thermal expansion and large negative thermo-optic coefficient of SU-8, a shift toward shorter wavelengths is expected. In the experimental evaluation, a negative wavelength shift from 1542 nm at 20 degrees C toward 1527 nm at 56 degrees C is obtained with approximately -0.42 nmK(-1) matching the theoretical considerations. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)