Laser with Injected Squeezed Vacuum: Phase Diffusion and Intensity Fluctuations

Perry Rice, Xiaosong Yin**, James Walden*, Julio Gea-Banacloche (U. Arkansas), Leno Pedrotti (U. Dayton), and Jack Mullen* (U. Dayton) -- Physical Review 50, 4176 (1994)

Abstract: We investigate the effect of injected squeezed vacuum on the phase and intensity fluctuations of a laser. By using a stochastic simulation of the Langevin equations, we find that the phase diffusion noise of a laser with injected squeezed vacuum can be transiently reduced by a factor of two, in agreement with earlier predictions. Further, we find that the laser linewidth is broadened. The key observation is that the phase diffusion rate is time dependent. We find that the steady-state intensity fluctuations are increased by the injected squeezing, in qualitative (but not quantitative) agreement with an earlier prediction. The problem of locking is examined. We find that the injected squeezed vacuum does not cause the laser to lock to any particular phase. We present an approximate analytic expression for the steady-state Fokker-Planck equation, and a simple geometrical, vector kick model from which most of our results can be obtained.