Interferometric switch

DETAILED DESCRIPTION It is therefore an object of the present invention to provide an optical switch that overcomes the heretofore noted disadvantages of prior an switches.
A further object is to provide a compact, low power, low cross-talk nonlinear optical switch.
Briefly, the monolithic interferometric switch according to one aspect of the present invention comprises input coupler means for splitting an input signal into N equal signal components, where N>1.
Combining means, having at least first and second output terminals, is provided for combining the N components.
N optical waveguide paths connect the N signal components to the combining means.
At least one of the waveguide paths contains a material having a resonant nonlinearity, whereby its refractive index changes when pump power propagates through it.
The input coupler means and the combining means are free from nonlinear material.
The input coupler means, the combining means and the optical waveguide paths are in thermal contact with a matrix glass body.
In one embodiment the switch consists of first and second optical fibers extending longitudinally through an elongated body of matrix glass.
The body includes a phase shift region and two spaced coupler regions at opposite ends of the phase shift region.
The diameter of the body and the diameters of the fibers are smaller in the coupler regions than in the phase shift region At least that portion of the first fiber that is in the phase shift region contains a material having a resonant nonlinearity, whereby the refractive index of the first fiber changes when pump power propagates through it.
The fibers have different propagation constants in the phase shift region in the absence of pump power propagating through the first fiber so that the first fiber subjects the light propagating therethrough to a delay that is different from the delay experienced by light propagating through the second fiber.
According to a further aspect of the invention, an interferometric switch such as a Mach-Zehnder switch or other intefferometric switch, includes first and second optical couplers and first and second optical paths extending between these couplers