Abstract

The fiber loop mirror,¹ consisting of a fiber directional coupler with its output ports spliced, has been very successful in demonstrating nonlinear switching in an all-fiber device.^2,3 For a nonsymmetric coupler, i.e., the power coupling coefficient, α ≠ 0.5, the signals propagating in opposite directions in the loop experience different intensity-dependent phase changes. This gives rise to a transmissivity which is a function of light intensity. For example, in the linear (low power) limit, the expected transmissivity for α = 0.4 is ~0.04, and the loop, therefore, acts as a broadband high reflectivity mirror.

© 1990 Optical Society of America