Resonant grating filters at oblique incidence

We designed a tunable, oblique incidence resonant grating filter covering the c-band as drop device. Our resonant grating filter consists of a planar waveguide on a glass substrate covered by low index medium that separates the waveguide from the grating on top of it. With these 3 layers we reach a finesse of more than 3000, which would require much more layers in traditional thin film technology. The drop filter can be tuned by tilting the MEMS platform on which the filter will be glued. Tuning over the c-band will require tilt angles of 3° of the MEMS platform in both directions. Measurements indicate a resonance peak shift of 1.2% and a negligible shape change of the resonance peak from 1526nm at 45° angle of incidence to 1573nm at 53° with a full width at half maximum of 0.4nm. In this range the peak wavelength shift is linear with respect to the change of the AOI.