Bottom-Heating Approach for the Realization of Thermooptic Polymer Waveguide Devices

We propose a bottom-heating approach to realizing a thermo-optically tunable polymer waveguide device, where the electrode heater is deposited at the bottom of the waveguide through a hole-etched substrate. Compared with the conventional top-heating approach, the bottom-heating approach can provide more effective optical isolation from the electrode, reduce the risk of damaging the polymer material in the fabrication process, and simplify electric wiring. We demonstrate the idea experimentally with an ultraviolet written long-period grating on a polymer waveguide fabricated by an imprinting technique, which incorporates a bottom electrode heater for phase-shift tuning. The grating requires an electric power of 1.74 mW to produce a -phase shift.