High-efficiency, continuous-wave Raman lasers

A modified steady-state laser theory that describes a continuous wave (cw) off-resonant Raman laser with asymmetric reflectivities for the cavity is presented. This theory takes into account different mirror reflectivities of the front and back mirrors of the Raman laser cavity for both the pump and the Stokes wavelengths. An off-resonant cw Raman laser pumped at 795 nm in diatomic hydrogen (Hz) is modeled by use of the results of the steady-state theory. The predicted threshold for the cw Raman laser is 2.4 mW, and a maximum Stokes photon conversion efficiency of 83.0% is predicted for a pump power of 9.9 mW. The high Stokes photon conversion efficiency is obtained with mismatched pump-wavelength reflectivities of the front and the back mirrors of the laser cavity. By a judicious choice of mirror reflectivities, both the backreflected pump power and the transmitted pump power can be minimized, thus making a maximum amount of pump power available for nonlinear Stokes conversion. (C) 1999 Optical Society of America [S0740-3224(99)01405-8].