Electrically Tuned Optical Waveguide Filters

The evolution of next generation wavelength multiplexed lightwave systems for high capacity transport, distribution and switching will require highly functional integrated optic subsystems. A key element for such photonic circuits is an integrable, tunable filter/coupler. We review research efforts on tunable waveguide filters and examine their applications and requirements. Some emphasis is given to research activities in our laboratories on the InGaAsP/InP vertical coupler/filter and photonic circuits based on it, including a widely tunable laser and amplifier/filter.