Optical Fiber Kerr Switch: A New Twist

Abstract

Methods for photonically switching optical signals in solid state devices made of LiNbO3 or GaAs have long been the object of intensive research. More recently, switching in optical fibers has been considered as well. In this presentation, we consider a scheme first proposed by Shirasaki, et al.1 In their scheme, one of the two nearly degenerate modes of a single-mode fiber is the transmission channel while the other mode is the switching channel. The two channels interact through the Kerr effect. As shown in Fig. 1, we may use a Mach-Zender interferometer configuration. If we inject the signal pulse into both arms and then inject the switching pulse into the second arm, it is possible to use the switching pulse to alter the phase of the signal pulse in the lower arm so that it interferes destructively with the signal pulse in the upper arm. Without the switching pulse, the two signal pulses interfere constructively. In order to avoid the effect of fluctuations, the two arms are temporally, not spatially, separated.1