Nonlinear optical spectroscopy of (3) in LiNbO3

By using tunable dye lasers, the third-order optical nonlinear susceptibility (3)(-3,1,1-2) is studied in LiNbO3. (3) shows resonant enhancement when 1-2 is near the polariton frequencies. This behavior is explained in terms of a nonlinear force which drives the polariton modes strongly whenever momentum matching is satisfied. © 1972 The American Physical Society.