301-nm wavelength tunable differentially driven all-polymer optical filter

Abstract

An optical filter based on all-polymer grating-assisted directional coupler is demonstrated. The wavelength tuning is differentially driven. The heater-electrodes created on the sidewalls of the polymer ridge can either blue- or red-shift the central wavelength. A total tuning range of 301 nm is achieved experimentally. The maximal local temperature gradient introduced across the coupler region is only 55°C–68°C. The filter is also insensitive to uniform ambient temperature change. Central wavelength jitter of $\pm 3\mathrm{nm}$ is observed when the chip holder temperature cycles between 20°C and 80°C.