EFFECTS OF DIFFERENT PHASE-MATCHING CONDITIONS IN SUM-FREQUENCY-MIXING SYSTEMS IN VAPORS

We have examined the effect of various phase-matching conditions on su m-frequency generation in vapors. Using sodium vapor two resonant-enha ncement routes for sum-frequency mixing (SFM) via a second-order magne tic-field-induced nonlinearity were explored. On one route the output is resonant with a quadrupole-allowed transition and the other a dipol e-allowed resonance. We will show that the first route is preferential for SFM as phase matching on this route is easier to control and we p resent results detailing the important parameters and their effect in focused and unfocused cases. A second-order nonlinearity of 0.5-1 pm V -1 is observed under optimum conditions. In the second route, variatio ns in phase matching as one tunes across the transition may lead to a significant distortion of the spectroscopic line shapes. We show how t he combination of different refractive-index sources can account for t he different features seen.