Abstract

We present the results of numerical and experimental investigations into the behavior of multi-mode dye lasers. In an experimental investigation of a two-mirror concentric-cavity dye laser, we find that the individual-mode-intensity fluctuations are qualitatively different from those in a three-mirror laser. The fluctuations in the two-mirror laser display a switching behavior in which the average time that each mode is off can exceed the average time that it is on. The time-averaged optical spectrum is found to contain many modes at all pump powers, which is in contrast to results from a three-mirror laser. The rf spectum of the total intensity indicates that spatial hole burning significantly affects which modes lase simultaneously. The fluctuation behavior of the mode amplitudes in an ideal three-mirror dye laser near threshold is investigated numerically. We have determined how near to threshold the laser must be operated so that quantum noise is the dominant cause of the intensity fluctuations of the individual modes. Higher above threshold the fluctuations caused by four-wave mixing of the laser modes in the gain medium dominate quantum fluctuations.

© 1988 Optical Society of America