Abstract

Starting from Lamb’s well-known equations of motion, the evolution of the phases in the oscillating modes of standing-wave lasers has been studied numerically in situations where mode competition becomes important. The latter results from the fact that different modes are coupled to the same group of excited atoms, hence the condition for its occurrence is that the homogeneous linewidth of the active medium be larger than the mode spacing. While mode competition tends to quench modes that are discriminated by lower gain values (the cavity losses were assumed to be equal for all modes under consideration), there exist certain mechanisms such as spatial hole burning, spontaneous emission, and the presence of inhomogeneous line broadening (in addition to a homogeneous one) that counteract quenching and lead to mode coexistence, i.e., simultaneous laser oscillation in various modes.

© 1984 Optical Society of America