Abstract

In a fiber coupler made of two birefringent fibers or fiber cores, there are four channels for light transmission and mutual coupling: two polarizations in each waveguide. Cross-phase modulation exists between the two channels in the same waveguide. This phase modulation affects the energy coupling between the two waveguides. These effects are dependent on the birefringences of the fibers, the timing jitter, the relative phase, and the relative intensity of the input pulses. In the input energy level chosen, cross-phase modulation tends to add its contribution to self-phase modulation and to keep the input energy from coupling into the other waveguide. Hence, if a control wave is used in one of the waveguides and two signals are applied to the two polarizations of the other waveguide, by using the effects of cross-phase modulation between the pump and signals, and and nand all-optical ultrafast logic functions can be implemented. Simulation results for both cw and picosecond soliton signals are presented. Significant differences between cw and pulsed signals can be seen. Although fiber couplers are used for demonstration in this paper, the basic physical pictures shown are applicable to nonlinear couplers of any nonlinear materials.

© 1991 Optical Society of America