Optical fiber mach-zehnder interferometer fabricated with asymmetric couplers

摘要

An asymmetric optical fiber Mach-Zehnder interferometer (10) has first and second optical fibers (20,22) connected at a first coupling region (12) and a second coupling region (14). The first and second optical fibers (20,22) form two interfering arms (16,18) between the first and second coupling regions (12,14). To form the asymmetry, the propagation constant in a portion of the first optical fiber in one of the coupling regions differs from the propagation constant in a portion of the second optical fiber in that coupling region. The asymmetric structure provides 30 dB isolation over a greater wavelength span. Fiber Bragg grating (25,27) are written into the core (28,30) of each of the interfering arms (16,18). The asymmetric optical fiber Mach-Zehnder interferometer is used as a wavelength division multiplexer/demultiplexer.