Systematic description of laser phase by linearized Ito equations.
We show that well above threshold the use of linearized Ito quantum stochastic differential equation allow a systematic description of all quantum stochastic properties of laser light including the phase properties. This is accompanied by the use of mixed field-atom operators which are phase independent and around whose finite mean values we may linearize. As a consequence wee are able to derive an equation for an operator describing the phase properties of the laser light
Quantum Noise Reduction in Raman Lasers
We demonstrate that the intensity fluctuations of a laser with a Raman gain medium, described by a large number of independent 3-level atoms, can drop well below the shot noise level. In the limit of a good cavity, where one can adiabatically eliminate the atoms, we find an optimum Mandel Q parameter of Q ≈ −1/2 over a large range of parameters, when the laser is operated well above threshold. This leads to a strong suppression of the low-frequency quantum fluctuations in the laser output. In addition we find that due to suppression of spontaneous emission into the lasing mode, the spectral linewidth of the emitted light can be reduced below the Schawlow-Townes limit by more than one order of magnitude.
Quantum Theory of a Raman Laser
The quantum theory of a coherently driven optical cavity with an intracavity Raman active medium is presented. This system is shown to give rise to laser action at the Stokes frequency. A Fokker-Planck equation is derived for the Stokes mode and shown to assume the same form as that for the usual laser. The limiting noise in this Raman laser arose from the spontaneous decay of a pump photon into a Stokes photon and a phonon.