Computer simulation of laser photon fluctuations: Coupled-cavity lasers

This third paper of the series deals with photon fluctuations in the light output of coupled-cavity lasers. As before, statistics on laser photon fluctuations are collected from numerical solutions of noise driven rate equations. Compared to the single-cavity injection laser, the coupled-cavity laser is found to have the following advantages. 1) The coupled-cavity laser can be made to operate in a single mode by driving one of its sections above and the other below threshold. For a given amount of output power from the high-current end, fewer photon fluctuations occur if it is the longer laser section that is driven above threshold. 2) The order of magnitude of the photon fluctuations of the single lasing mode of a coupled-cavity laser is comparable to the fluctuations of the total power output of a single-cavity laser. 3) Contrary to single-cavity lasers, which cannot be made to operate in a single mode if they are driven by short current pulses, coupled-cavity lasers will readily deliver a single, pulsed mode. Thus, if thermal effects and backreflection of scattered light (for example, from an attached fiber) can be ignored, mode jumping need not occur.