No abstract

We show theoretically and experimentally that the positions of the fringes produced by interference between a wave incident upon a phase-conjugate mirror and the wave leaving the mirror depend on the phase associated with the incident wave. This result is in contrast to that obtained when an ordinary metal mirror is used, in which case the interference pattern is found to beindependent of the phase of the incident wave.

Results of an experimental investigation of phase conjugation by stimulated Brillouin scattering (SBS) at 1.053 pm using a focused beam geometry with very long pulse lengths (pulse length > 6700 phonon lifetimes) are reported.Scanning of the beam through the SBS medium is proposed as a means of suppressing the undesirable effects of processes which can compete with the SBS in the long -pulse regime. Data taken with and without beam scanning indicate that high -quality phase conjugation can be achieved by SBS using focused beams with arbitrarily long pump pulses.

The relay mirror concept involves deploying a passive optical station at a high altitude for relaying a beam from a laser weapon to a target. Relay mirrors have been proposed as a method of increasing the range of laser weapons that is less costly than deploying a larger number of laser weapons. Relay mirrors will only be effective if the beam spreading and beam quality degradation induced by atmospheric aberrations and thermal blooming can be mitigated. In this paper we present the first phase of a multi-year effort to develop a theoretical and experimental capability at Boeing-SVS to study these problems. A team from MZA and Boeing-SVS has developed a laboratory test-bed consisting of a distributed atmospheric path simulated by three liquid crystal phase screens, a Shack-Hartmann wavefront sensor, and a MEMS membrane deformable mirror. We present results of AO component calibration and evaluation, the system construction, and the system performance.

We have repeated the classic experiment of Wiener,1 which established the nature of the standing-wave pattern produced by reflection at the surface of a metallic mirror, with the metallic mirror used in his experiment replaced by a phase-conjugate mirror. We find that the positions of the fringes produced by interference between the wave incident on the phase-conjugate mirror and the wave leaving the mirror depends on the phase of the incident wave. This result is in contrast to that obtained through the use of a metallic mirror, in which case the interference pattern is found to be independent of the phase of the incident wave. The origin of the different behavior in these two cases lies in the fact that the phases of the waves that pump the PCM provide a reference through which phase information carried by the signal wave can be obtained. The experimental results are in excellent quantitative agreement with recent theoretical predictions.2