Low-power frequency conversion through parametric interaction and cascadedprocesses in a N-(4-nitrophenyl)-L-prolinol crystal

Crystals of N-(4-nitrophenyl)-L-prolinol (NPP) of large size and of high op tical quality are grown in methanol solution starting from toluene nucleate d seeds. Measurements are conducted on a 2.8 mm thick specimen obtained by cleaving a thick slice parallel to the (101) plane. This type of cut allows access to the dominant phase-matching orientation, including the noncritic al one. We exploit the high second-order susceptibility of NPP to produce v arious frequency conversion processes (second harmonic, parametric generati on and nearly-degenerate wavelength conversion through cascading) at a very low input intensity. In particular, frequency conversion of a signal pulse (from 1.16 to 1.14 mu m) under the action of a pump pulse (at 1.15 mu m) w ith unit gain is obtained with a pump intensity as low as 9 MW/cm(2), while parametric generation from quantum noise, with 10% conversion efficiency, is obtained in a single pass of the pump pulse focussed to an intensity aro und 10(8) W/cm(2). (C) 1999 Elsevier Science B.V. All rights reserved.