Thermally Tunable Silicon Nitride Sampled Gratings in Polymer

Sampled gratings based on low-loss buried silicon nitride waveguides in polymer have been fabricated and investigated. Low-temperature plasma enhanced chemical vapor deposition and standard photolithography are used to form the silicon nitride core layer directly on polymer. These gratings show a common peak interval of 7.3 nm but varying 3-dB mode numbers according to the design. Since the optical mode expands largely into the cladding, the thermo-optic effect of the polymer material dominates. With buried heating electrodes, wavelength tuning of 8.1 nm has been achieved at ~ 100 mW of electrical heating power.