Abstract

Nonlinear optical materials based on π-conjugated organic monomer and polymer materials have the potential to possess extremely large and fast nonlinear coefficients. The organic crystal (−)2-(α-methyl-benzylamino)-5-nitropyridine (MBA-NP) has attracted much interest because of its high optical damage threshold and extremely large χ⁽²⁾. We report on the observation of nonlinear optical effect of parametric hyper-Raman scattering in an ultra thin MBA-NP crystal. The nonlinear spectrum under 1054 nm excitation from 300-600 nm indicated that there are four distinct maxima located at 527 nm, about 560 nm, 351 nm, and about 364 nm. The signal at 527 nm and 351 nm are the second and third harmonic generations, respectively. Two new features are located at about 560 nm and 364 nm, which are shifted by phonon frequency from second and third harmonic generation signals, respectively. These signals may be from the parametric generation of the pump laser and its Raman scattering. A parametric instability theory is extended to quantitatively explain these experimental results.

© 1990 Optical Society of America