QUANTUM-NOISE PROPERTIES OF A CONSTANT-VOLTAGE-OPERATED SEMICONDUCTOR-LASER

Quantum-noise properties of a semiconductor laser under constant-voltage operation, where the laser-field amplitude is regulated through nonlinear gain, have been studied using quantum-mechanical Langevin equations. In the ideal constant-voltage-drift case, the linewidth enhancement from the gain-refractive-index coupling, as well as the relaxation oscillations, disappear, but for realistic nonlinear gains the amplitude noise will increase. The requirement on the laser's series resistance for constant-voltage operation is, however, very strict, and seems difficult to meet in practice.