Integrated Fabry-Perot Comb Filters for Optical Space Switching

The first implementation of an integrated filter for optical space switching based on coupled Fabry-Perot cavities built in a planar waveguide and working at oblique incidence is presented in this paper. Parabolic mirrors are used to collimate and direct light into a filter defined by deep etching in a GaAs waveguide and formed of four high-order cavities that provide a 200 GHz comb response. The filter has a theoretical passband bandwidth of more than 50 GHz and allows the switch to work over an entire wavelength band. It was possible to contain 50 channels of the International Telecommunication Union 100 GHz grid within the filter response. Bit error rate tests at 10 Gb/s were performed to evaluate the switch power penalty. To assess the scalability of this switch design, crossbar and shuffle Benes¿ layout for devices with 2-16 ports were optimized. The dominating factor that limits the minimization of a switch fabric area is the beam waist required to avoid distortion by the filters.