An analytic solution of the phase conjugate wave generated by degenerate-four wave mixing(DFWM), considering both the transmission and reflection gratings, in absorbing media is derived.
The solution is compatible with the theories of Yariv and Abrams. In order to prove the several specific aspects of the theoretical results, the experiments of DFWM is performed using the cryptocyanine dissolved in methanol as an absorbing medium, where the pump beam intensities are below the saturation of the absorbing medium ( 10M/㎠ ) and Q-switched ruby laser is used as the light source. The results experimentally obtained agree with the theoretical predictions.
In order to amplify the phase conjugate signal, the double-pass amplification is performed positioning amplifier in the path of the probe beam. The phase conjugate signal is amplified four times when time delay between the flash lamp triggering signal of the amplifier and the laser beam from the oscillator is 1msec. The flash lamp input energy is 648J. To interprete the experimental results, the theory of double-pass amplification developed by Balashov et al. is adopted. The analytic solution of the reflectivity and the theory of double-pass amplification give correct interpretation of the obtained amplified reflectivity.