Grating-assisted codirectional coupler filter using electro-optic and passive polymer waveguides

Abstract

We have proposed and demonstrated a band-rejection filter based on the grating-assisted forward coupling between an electro-optic (EO) polymer waveguide and a passive polymer waveguide. The passive polymer waveguide is used as a low-loss optical path and the EO polymer waveguide is used for dropping the optical signal at a given wavelength. The grating is etched on top of the EO polymer waveguide, which satisfies the phase-matching condition for the power exchange between the two asynchronous waveguides. We have poled the proposed device to have the EO effect and investigated changes of the filter characteristics induced by the poling process. As an experimental result, we have achieved a filter bandwidth of 2.5 nm with a device length of 10 mm. In addition, EO wavelength tuning of this filter has been demonstrated.