Polarization-independent filtering in a grating-assisted horizontal directional coupler

We report here on the design and the first realization of a grating-assisted horizontal directional coupler filter exhibiting a highly reduced polarization sensitivity. The filter, which is based on InP-InGaAsP materials, is particularly suitable for integration in a 1.3/spl plusmn/1.3 μm duplexer. A polarization dependence below 1 dB has been measured for the separation of two 10 nm wide channels, respectively centered at 1.28 μm and 1.32 μm, for a rejection ratio of 10 dB.