Ring resonator lasers using passive waveguides and integrated semiconductor optical amplifiers

We present a review of our work on ring lasers using passive waveguides; and couplers (directional and multimode interference) integrated with semiconductor optical amplifiers (SOAs). Two architectures are given in this paper. The first architecture includes the SOA inside the ring cavity. The second architecture also known as ring resonator coupled laser, consists of passive ring resonators having SOAs in the bus waveguides. The increased photon lifetime in the cavity and the tunability of the ring response can be used to make compact, narrow linewith, and widely tunable lasers. Four-wave mixing applications are also addressed.