Optical waveguide interferometer modulator-switch

Abstract

An optical waveguide arrangement operates in the manner of an interferometer to provide modulator and/or switching functions. Two optical waveguide branches having a common connection diverge along a substantially coextensive distance and reconverge to provide first and second light paths of identical optical length. Conductive electrodes are disposed contiguous to at least one of the optical waveguide branches and are connectable through a controlling switch to a source of electrical energy for producing an electric field across the energized electrodes. In the absence of such electric field, light energy entering the two optical waveguide branches will propagate along identical optical path lengths and recombine constructively at the reconvergence of the waveguide branches. However, a selectively applied electrical energy changes the optical property of at least one of the optical waveguide branches causing phase differences in the optical energy transmitted by the branches and producing destructive interference at the reconvergence of the optical waveguide branches. The addition of two optical waveguide sections having different dimensions provides a switch function when one of such additional waveguides is dimensioned to be conducive to the propagation of first order mode light energy while the other waveguide is dimensioned to be conducive to the propagation of second order mode light energy.