ABSTRACT
The rapid growth in the development of optical networks requires small, inexpensive, and easy-to-integrate optical amplifiers for use as basic amplifiers and also as optoelectronic signal processing devices such as wavelength converters, optical switches, intensity and phase modulators, logic gates, and dispersion compensators. There are two main classes of optical amplifier: optical fiber amplifiers and semiconductor optical amplifiers (SOAs). The amplification process adds broadband noise to the propagating signal, caused by spontaneous recombination of conduction band electrons to valence band holes. SOAs that use bulk materials require high transparency current densities. The simple model described above illustrates SOA operational principles, in particular, saturation effects, but it is of limited use in a real SOA analysis. XGM-based wavelength converters suffer from the disadvantage that high-input pump powers are required to obtain the large SOA gain modulation depth necessary to achieve a large converted signal extinction ratio.
