Fine structure of the field autocorrelation function of a laser in the threshold region

Abstract

Autocorrelations due to natural phase and amplitude fluctuations of the laser field were investigated in the threshold region of a 633-nm He-Ne single-mode laser by use of an' interferometric autodyne method. The measured time-dependent autocorrelation function shows deviations from gn exponential decay that can be described by a formal fine structure predicted by the theoretical Van der Pol laser model. As a consequence, the natural laser spectrum is not exactly Lorentz shaped. The natural linewidth shows the expected general reciprocal power dependence and an additional factor-of-2 narrowing above threshold, in full agreement with the theory.

Nonlinear features of quantum fluctuations in a slow-inversion laser

“…These problems were studied in previous publications using a class-A laser description (see, for example, Refs. [2][3][4][5][11][12][13]) and also for a bad-cavity laser (when c γ p ,γ N ) [14,15]. In all these studies the relative intensity fluctuations above threshold are low and thus the effect of intensity fluctuations on the linewidth can be neglected.…”