Ferromagnetic Composite Optical Isolator Monolithically Integrated with a Semiconductor Laser

"This proposal describes a new method to achieve optical-waveguide isolators that can be integrated with a variety of material systems. The isolators use Ferromagnetic Composites (FC) in conjunction with the magnetic Kerr effect. Isolators integrated onmaterials used in semiconductor lasers and isolators integrated on glassy materials used in optical fibers have been designed and their performance calculated. Correct design, which has heretofore not been realized, results in strong overlap fields in themagnetic composite layer in one direction and much weaker fields in the other. This non-reciprocal change in the overlap fields effectively magnifies the magnetic Kerr effect and results in the good isolation to loss ratios of our designs. Prior to thisdesign breakthrough waveguide isolators that could be monolithically integrated with other waveguide devices had such high insertion loss as to be impractical even when coupled with the high gain of semiconductor lasers.Our principal Phase I objective is the experimental demonstration of an optical waveguide isolator integrated on semiconductor material with high isolation and high isolation to loss ratio. Semiconductor lasers, particularly at high power, must be isolated from reflections from the transmission medium back into the laser in order to avoid instabilities. In area of telecom lasers, a discrete isolator is manually positioned between the laserand the fiber during assembl