Effects of Pump Phase Noise on the Linewidth of a Λ-Laser Without Inversion: Linewidth Reduction

The effects of the pump phase fluctuation on a Λ-laser with and without inversion are investigated. It is shown that the pump phase fluctuation can reduce the linewidth of the laser without inversion. It is also shown that, when the system exhibits a transition from lasing without inversion to lasing with inversion, the laser linewidth can still be reduced.