SiC nanocrystals embedded in oligoetheracrylate photopolymer matrices; newpromising nonlinear optical materials

Photoinduced optical phenomena in SiC nanocrystallites embedded within the photo-polymer oligoetheracrylate matrices have been studied using experimen tal nonlinear optics, particularly photoinduced optical second harmonic gen eration (SHG). The YAG-Nd-laser (lambda = 1.06 mu m; W= 30 MW, pulse durati on within the 30-50 ps) was used as a source of pumping light and the nitro gen laser (lambda, = 337 nm) has been applied as a source of the photoinduc ing light. With increasing intensity of the photoinducing beam, the SHG (la mbda = 0.53 mu m) signal increased and achieved a maximum (chi(222) = 10.1 +/- 0.13 pm/V) at a photon flux of about 1.61 GW/cm(2). With decreasing tem perature, the SHG signal strongly increases within the temperature range 25 -30 K. Time-dependent probe-pump measurements indicate an existence of the SHG maximum for a pump-probe time delay of about 20 ps. The SiC hexagonal s tructural components play a key role in the observed photoinduced nonlinear optical effects. Large values of the nonlinear optical constants as well t he good technological parameters open a possibility to enhance the nonlinea r optical susceptibilities. (C) 2000 Elsevier Science B.V.. All rights rese rved.