All-optical switch using multi-terabit/sec pulses

Summary form only given. The demand for communications bandwidth is growing rapidly necessitating novel all-optical devices. Optical signal processing will be needed for many functions such as regeneration, clock extraction, and switching. In particular devices that are compatible with optical fibers are desirable. Optical switching in dual-core or multiple-core nonlinear fibers is being examined extensively. A significant area of work has been in soliton or solitonlike pulses. The optical power is exchanged between the coupled waveguides because of the weak overlap of the evanescent fields. The nonlinear directional coupler functions in the following manner; for low input power the light beam is transferred from one waveguide to the other but for high input power the light beam remains in the same waveguide. The result is power dependent all-optical switching. To date results have been presented for picosecond (and /spl sim/100 femtosecond) duration pulses. The optical switching process is described by coupled nonlinear Schrodinger equations including self-phase modulation (SPM), group velocity dispersion (GVD), cross phase modulation (XPM), and a linear cross-coupling coefficient. However, as bit rates extend into the multi-Tb/s region, ultrashort pulses (<100 fs) are required, and higher-order terms must be included in the coupled equations. Using the numerical beam propagation method we have shown multi-terabit/sec (i.e. pulse durations below 100 fs) all-optical switching in a dual core dispersion-flattened fiber. These devices may play a role in ultrahigh bit rate communications systems.