All-optical waveguide devices based on multiple quantum wells

This contribution focuses on optically-controlled switching devices that have the potential of operating at rates greater than 40 Gb/s, that is beyond the limits of electronics components. These devices would be useful for ultrafast serial processing: applications include routing and time-domain demultiplexing in telecommunications transmission networks as well as local area networks, providing key functions where the system bottleneck is set by the bandwidth of a few critical components. All-optical time-domain switching and routing is a natural complement to wavelength switching in offering massive transport capability: therefore, it would be advisable that optically-controlled technologies be compatible with wavelength switching implementations. The discussion here is restricted to nonlinear, guided-wave, passive devices based on semiconductors, and, specifically, on semiconductor quantum wells (SQWs).