EFFECT OF IDLER ATTENUATION ON SPONTANEOUS PARAMETRIC SCATTERING OF INTENSE LIGHT IN LINBO3 AND NH4H2PO4

The forward-scattered intensity in the spontaneous parametric process is found to decrease significantly as the idler frequency goes sufficiently far into the 5.7- and 1.4- infrared absorption bands of LiNbO3 and NH4H2PO4, respectively. These results indicate that, unlike the previously studied cases in GaP and LiNbO3, the corresponding optical nonlinear susceptibility has essentially no resonance increase and its ionic contribution remains small near these absorption bands. A formula for the forward-scattered intensity is obtained which agrees very well with the observed effects of idler attenuation on the spontaneous parametric scattering in both LiNbO3 and NH4H2PO4. © 1969 The American Physical Society.