All-optical, fiber-optic modulator and logic gate using nonlinear refraction and absorption

The first demonstration to our knowledge of new all-optical logic gates and modulators that use nonlinear refraction and absorption to modify fiber-to-fiber coupling is reported. Results are presented for the AND, NOR, NOT, and XOR functions with better than 20-dB contrast ratio. Silicon (at lambda = 1.06 microm) is used as the nonlinear material for this proof-of-concept experiment. No resonators, feedback, or stringent wavelength controls are needed. The feasibility of picosecond operation is discussed.