Raman phase conjugate resonator for intracavity aero-optic turbulence aberration correction

A cw degenerate phase conjugate resonator (PCR) with intracavity aero-optic turbulent flow is demonstrated using sodium vapor pumped with a low intens ity cw laser. A turbulent helium jet at a high flow velocity of 250 m/s and forcing frequency of 18 kHz generated the spatio-temporal aberrations. The intracavity normalized peak-to-peak intensity fluctuations at 18 kHz measu red with a pinhole-detector are ten times smaller in the corrected beam tha n in the aberrated beam. The threshold pump intensity for the resonator is similar to 4.5 W/cm(2) in the absence of the turbulent flow. The pump frequ ency is tuned well within the Doppler width of the Na D-1 transition. Evide nce of a degenerate (laboratory frame) double-Lambda mechanism involving Ze eman sublevels is also shown. (C) 1999 Published by Elsevier Science B.V. A ll rights reserved.