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

Ž . A cw degenerate phase conjugate resonator PCR with intracavity aero-optic turbulent flow is demonstrated using sodium vapor pumped with a low intensity cw laser. A turbulent helium jet at a high flow velocity of 250 mrs and forcing frequency of 18 kHz generated the spatio-temporal aberrations. The intracavity normalized peak-to-peak intensity fluctuations at 18 kHz measured with a pinhole-detector are ten times smaller in the corrected beam than in the aberrated beam. The threshold pump intensity for the resonator is ;4.5 Wrcm in the absence of the turbulent flow. The pump frequency is Ž . tuned well within the Doppler width of the Na D transition. Evidence of a degenerate laboratory frame double-L 1 mechanism involving Zeeman sublevels is also shown. q 1999 Published by Elsevier Science B.V. All rights reserved. PACS: 42.65.yk; 42.65.Hw; 42.50.Gy; 42.60.Da; 42.55.Ye