Variable demultiplexing using a twin-core fiber Mach-Zehnder interferometer

A novel form of demultiplexer is demonstrated using a single untapered length of twin-core fiber. The degree of demultiplexing can be varied so that an arbitrary amount of power at a given wavelength (e.g., 1.3 mu m) can be removed from a multiplex to two wavelengths (e.g., 1.3/1.55 mu m). The variation is achieved by locally bending the fiber in the plane of the twin cores. Channel spacings of 30 nm have been achieved experimentally.<>