ABSTRACT
Optical non-linearities of semiconductor lasers and semiconductor optical amplifiers (SOAs) create many different types of optical devices with new functions. These devices are expected to become the key devices in optical communication and signal processing systems. The great advantage of these functional devices is that they have optical gain. Thus, the device can be operated by optical control signals with low power. The output signals are stronger than those of input signals in many cases. In addition, some mechanisms for these non-linearities have ultrafast response times, which enable the optical functional devices to operate with very high speed. Optical bistability is a unique phenomenon which can be applied to all-optical memory operation.
