Interferometric switch

A monolithic Mach-Zehnder switch comprising

• an elongated body of matrix glass,
• first and second optical fibers extending longitudinally through said body,
• a phase shift region in said body,
• two spaced coupler regions in said body at opposite ends of said phase shift region, the diameter of said body and the diameters of said fibers being smaller in said coupler regions than in said phase shift region,
• at least that portion of said first fiber that is in said phase shift region containing a material having a resonant nonlinearity, whereby the refractive index of said first fiber changes when pump power propagates through it, said fibers having different propagation constants in said phase shift region in the absence of pump power propagating through said first fiber so that said first fiber subjects the light propagating therethrough to a delay that is different from the delay experienced by light propagating through said second fiber.

An interferometric switch comprising at least three optical couplers and a plurality of optical paths extending between said couplers in groups so that said couplers are connected to one another in series by said groups of fibers, each such group including at least two said paths in parallel with one another, one of said couplers being an input coupler at one end of said series, another one of said couplers at an opposite end of said series being an output coupler, the device further including means defining a signal input port connected to said input coupler and a first output port connected to said output coupler, each said path having an optical path length between said couplers, at least one of said paths being a nonlinear path including a material having a resonant nonlinearity such that the refractive index of said material and the path length of the nonlinear path changes when optical power propagates through such path, said path lengths of the paths in at least one said group being different from one another in the absence of said optical pumping power, said device having a zero-power transfer function relating the proportion of light supplied through said first input port which appears at said first output port to wavelength in the absence of said optical pumping power, said zero-power transfer function including a peak at a first wavelength at which substantially all of the light appears at said first output port and a valley at a second wavelength at which substantially none of the light appears at said first output port.