NOISE STUDY OF LOW-DIMENSIONAL QUANTUM-WELL SEMICONDUCTOR-LASER AMPLIFIERS

Low noise characteristics of semiconductor laser amplifiers (SLA's) consisting of low-dimensional quantum-well structures are theoretically obtained from density matrix theory. Due to sharper gain spectrum as well as smaller population inversion parameter in quantum-wire and quantum-box structures, predominant two beat noises of traveling-wave semiconductor laser amplifiers (TW-SLA's) were found to be reduced in the lower dimensional quantum-well structures, even in solitary devices without a narrow band-pass filter. The noise figure can be reduced to 3.3 dB in a quantum-box structure, which is almost the theoretical limit of 3 dB.