Abstract: An optical fiber amplifier has a lossy nonlinear medium connected between its input port and its output port. The resultant optical feedback loop permits remote gain switching of the optical amplifier.

Abstract: An optical branching waveguide having low radiative loss and low back-reflectivity is described. By employing between the branches a region having a gradual decrease in effective refractive index along the direction of optical propagation, the deleterious effect of wedge tip truncation can be reduced. According to the teachings of the invention, this may be accomplished by gradually decreasing the thickness of the optical material along the axis of optical propagation and planarizing the region with an optical material having a lower refractive index than the underlying optical material.