Design of a polymer photonic crystal membrane cavity for channel drop filtering in coarse wavelength division multiplexing networks

A low-cost polymer integrated optical filter for coarse wavelength division multiplexing systems has been modelled, designed and optimized. The device, which can be manufactured by nanoimprinting lithography, is a Fabry-Perot cavity working at 1551 nm and consisting of a membrane-type slab photonic crystal in which a hole row perpendicular to the propagation direction is removed to form the two reflectors. The dependence of the resonator performance on the key geometrical parameters, i.e. the hole radius and the defect length, has been investigated by the finite element method. A good agreement between the requirements due to the specific application and the device performance has been obtained. The optimized filter, with a footprint of 43.7 μm², has a Q-factor of 115 and a resonance transmission > 50%.