Phase conjugation of 2.91-μm HF laser radiation via stimulated Brillouin scattering

Abstract

We report the results of experiments demonstrating stimulated Brillouin scattering (SBS) and phase conjugation of a single-line HF laser. The 2.91 μm was selected by an intracavity grating yielding up to 3J in a 1.5-μS pulse. The flat-flat optical cavity was carefully aligned to maximize far-field intensity and the resulting spot diameter was found to be near the diffraction limit. The magnified far-field intensity profiles were imaged with film burns and with a linear pyroelectric array. This high spatial quality beam was intentionally distorted by passing it through a roughened NaCl window and the distortion was verified by examining the far-field intensity profile. This distorted beam was then focused into a cell containing xenon at 45 atm. The resulting SBS reflection passed back through the NaCl aberrator and the diffraction-limited far-field intensity profile of this reflected beam was found to be restored. This demonstration of random phase aberration and reconstruction of the laser beam provides evidence that the SBS reflection is the phase conjugate of the input beam. (12min)