REAL-TIME ATMOSPHERIC COMPENSATION BY STIMULATED BRILLOUIN-SCATTERINGPHASE-CONJUGATION

We report the first demonstration to our knowledge of atmospheric comp ensation at extended ranges by stimulated Brillouin-scattering phase c onjugation. With a field-of-view aperture product of 175 mm mrad, we s tudied horizontal ranges up to 6 km at a 2.5-m height above ground, wi th the refractive-index structure parameter C-n(2) as large as 10(-13) m(-2/3). Compensation was achieved at all ranges, consistent with the turbulence-resolution capability of the 10-cm system aperture. The sy stem was driven by frequency-doubled Nd:YAG lasers operating with simi lar to 10-ns pulses that were Raman shifted in gaseous hydrogen to the 683-nm operating wavelength. Raman amplification overcame as much as 85 dB of range and internal losses.