Juan F. Lam

Optical resonators with phase-conjugate mirrors

The operating characteristics of optical resonators with phase-conjugate mirrors are discussed. Degenerate four-wave mixing is assumed to be the process giving rise to the phase-conjugated phase fronts. We have found that these resonators are unconditionally stable, have no longitudinal mode conditions that invoke the length of the cavity, and have smooth transverse mode structures. Computer simulation results pertaining to the properties of the lowest-order modes and the effect of mirror errors on these modes are also discussed.

Degenerate four-wave mixing in plasmas.

We report an analysis of degenerate four-wave mixing in uniform plasmas and show that the magnitude of the third-order susceptibility (varying as lambda(2)) can be comparable to (10(-11) esu for lambda = 10.6 microm) or orders of magnitude larger (10(-3) esu for lambda= 10 cm) than the corresponding susceptibility in typical nonlinear materials. The nonlinear contribution to the macroscopic current resulting from the ponderomotive force is generated from the two-component fluid model by means of a linearized perturbation scheme. Numerical estimates of the nonlinear susceptibility show that relatively large signals can be produced easily without significant problems from competing physical phenomena such as self-focusing or stimulated Brillouin and Raman scattering.

Multiline phase conjugation in resonant materials.

We present a direct experimental demonstration of multiwavelength phase conjugation through degenerate four-wave mixing. The experiments were performed using a multiline CO2 TEA laser with SF6 as the nonlinear medium. Using a vidicon to observe the signal in the far field, we show good aberration-correction ability. A qualitative description of the additional cross coupling is also provided.

On the equality of stimulated Brillouin scattering reflectivity to conjugate reflectivity of a weak probe beam

If a strong pump wave, with energy that is above threshold for stimulated Brillouin scattering, and a weak probe wave are incident into a nonlinear medium, then it has been shown by others that the reflectivity of the weak probe is equal to the reflectivity of the strong pump and that the probe is phase conjugated provided that the pump is phase conjugated. We present an analysis that predicts an exact equality of the reflectivities and identifies the parametric limitations.