Spectral changes in Gaussian-cavity lasers

Spectral changes occurring to laser radiation originated from amplified stimulated emission are evaluated as a function of the number of transits performed inside a Gaussian optical cavity. It is shown that the spectral shifts on the optical axis are quite different from those already established for Gaussian Schell-model beams and that pulsed lasers deliver pulses whose peak frequency slightly changes from the beginning to the end of the pulse.