Abstract

Mach-Zehnder devices are used in planar-optical-waveguide circuits (e.g., lithium niobate components), but simple fiber- based versions are not available. This results from the fact that these fiber-based devices, which are assembled from two 3-dB couplers and fibers of different lengths, are bulky and environmentally unstable. The two arms of the device can be subjected to thermal gradients and arbitrary bending and twisting, thereby affecting the device’s modal interference pattern. In an interesting fiber-based approach, nontraditional wavelength selectivity has been achieved by Malo et al.¹ in a device composed of fibers of different propagation constants and highly- wavelength-dependent couplers that were not of equal splitting. These devices as configured are also unstable with respect to arbitrary perturbations in the region between the couplers.

© 1994 Optical Society of America