Reversible and irreversible index gratings in a NPP-doped low-Tg polymer composite

Abstract

A reversible photorefractive grating and an irreversible local photo-induced aggregation grating were observed in a low glass transition temperature polymer composite poly(N-vinylcarbazole): 2,4,7-trinitro-9-fluroenone: N-ethylcarbazol: N-(4-nitrophenyl)-(l)-prolinol. Two gratings were distinguished by using the two-beam coupling (TBC) experiment and the four-wave mixing experiment. For photorefractive grating, the TBC coefficient was measured to be 140 cm−1 at an applied electric field of E0 = 85V/μm, corresponding to a photorefractive grating of 3.6 × 10−3. The photo-induced aggregation grating was measured to be about 7 × 10−3.