Multi-photon-absorption-induced birefringent grating in azobenzene-doped polymethyl methacrylate optical fibres

Abstract

Birefringent gratings induced by absorbing multi-photons at 532 nm in azobenzene doped polymethyl methacrylate (azo-PMMA) fibres were investigated. The maximum photo-induced birefringence observed from the fibre is about 3.0 × 10−5. The two-photon absorption coefficient β of the azo-PMMA at 532 nm obtained by the Z-scan method is 10.2 cm GW−1, and the birefringence response time of the azobenzene is 10 μs.