A polarization-independent coupled-waveguide grating resonator filter

Conventional resonant filters are polarization sensitive due to the modal birefringence as well as the polarization-dependent grating coupling and modal losses/gains. To reduce or eliminate the polarization sensitivity, we have proposed a polarization-independent grating resonator where the signal within the stopbands is reflected back to the same waveguide. In order to separate the reflected signal from the input signal spatially, we propose a polarization-independent coupled waveguide resonator filter and illustrate its design procedure with an example