Recording and self-enhancement of dynamic polarization gratings in degenerate four-wave-mixing geometry

Abstract

Scalar and vectorial degenerate four-wave-mixing (DFWM) in azobenzene molecular K-RJ-4-3 [N,N-bis(5,5,5-tryphenylpentyl)-4-((4-tritylphenyl)diazenyl)aniline] and in chalcogenide a-As 2 S 3 glassy films is experimentally investigated. A coherent self-enhancement (CSE) of holographic gratings (HG) in this geometry was experimentally confirmed, for the first time to our knowledge, thus establishing a new method of HG recording, the DFWM CSE recording. Scalar linear s-s, p-p and circular R-R(right) polarizations and orthogonal linear s-p and circular L(left)-R polarizations were used for HG recording with 2 µm period at 532 nm. In the case of K-RJ-4-3 film L-R polarizations were the most efficient enabling the maximum DFWM efficiency ρ max =14.5% whereas in the case of a-As 2 S 3 film s-s polarizations were the best with ρ max =6.0%. DFWM CSE recording has exhibited a different polarization dependence compared to normal DWFM recording. CSE factor ρ/ρ 0 (ρ 0 being the initial ρ) was the highest for K-RJ-4-3 film (6.8) with s-s polarizations compared to 3 for a-As 2 S 3 film with p-p polarizations. Two-wave HG recording was also studied for comparison.