Photon statistics and laser linewidth for microcavity semiconductor lasers.

摘要

In this dissertation, we have extended the quantum theory of microcavity semiconductor lasers, developed by Sokol and Pedrotti, to include a determination of the laser linewidth. In addition, we developed a flexible numerical code using the C programming language in which the theory was implemented in order to calculate photon statistics and laser linewidth for a variety of semiconductor microcavity laser systems. We find that the threshold peak in the variance over the mean photon number occurs at the pump rate at which the photon number distribution transitions from a thermal-like to a peaked distribution indicative of the onset of coherent output. We found that, so long as the cavity losses rate is more than the rate of spontaneous emission to the cavity mode, the laser intensity noise decreases with the increase of the fraction of spontaneous emission into the laser mode, while the laser linewidth increases, for the same output photon number, as this fraction increases when the cavity loss rate is less than the spontaneous emission rate into the cavity mode the intensity noise and the laser linewidth both increase with an increase in the rate of spontaneous emission into the cavity mode. We find that the microcavity semiconductor lasers are noisier than atomic microcavity lasers with similar output versus pump characteristics. We find a novel-operating regime, in which the spontaneous emission into laser mode exceeds the cavity loss-rate. The theory developed here is based on the Scully-Lamb quantum theory of the laser and presumes that the electrons in the conduction band and the holes in the valence band are in quasithermal equilibrium throughout the lasing process. The predictions of this theory are compared to experimentally determined noise properties of semiconductor lasers and the predictions of the noise properties of atomic microcavity laser systems.