A quantum electrodynamical treatment of second harmonic generation throughphase conjugate six-wave mixing: Polarization analysis

The theory underlying a six-wave mixing experiment is developed using the m ethods of molecular quantum electrodynamics. This general theory allows the intensity of the second harmonic radiation generated by the six-wave proce ss to be found for arbitrary arrangements of the generating laser beams. Se veral different polarization geometries are treated in detail, and comparis on is made to experiments performed using near-resonant conditions. The agr eement is good in all cases and allows detailed information pertaining to t he six-wave tensor to be extracted. The information thus obtained provides evidence of a marked departure from Kleinman symmetry. (C) 1998 American In stitute of Physics. [S0021-9606(98)01948-5].