Tunable silica-on-silicon planar lightwave circuits for signal processing applications

The development of silica planar lightwave circuits (PLCs) employing multiple phase-shifting elements to achieve optical signal processing is presented. Thermo-optic switching in Mach Zehnder interferometer (MZI) structures has been demonstrated with typical switching powers of 250-300 mW. 6-loop lattice-form MZI devices designed with specific filter responses have been fabricated, packaged, and tested. 10 GHz to 40 GHz pulse repetition rate multiplication has been achieved, and the tunability of the 6 phase control elements allows the generation of arbitrary 4-bit binary code patterns. Further improvements in complexity, power consumption, loss, and polarization sensitivity in these devices are discussed.