Short-pulse-induced thermal lensing effect in 1,2-dichloroethane and 1,2-dibromoethane

摘要

( )1,2-dichloroethane (C2H4Cl2) and 1,2-dibromoethane (C2H4Br2) show linear absorption (LA) and stimulated light scattering in response to the excitation by 820 nm 18 fs laser pulses. Using the Z-scan technique, with these pulses separated by 12.2 ns (much shorter than both samples' thermal diffusivity time constants tau(th)'s) and extended over 41 ms (considerably longer than tau(th)'s), we investigated the thermal lensing effect of both samples and found that LA dominates their heating. In addition, relative to C2H4Br2, C2H4Cl2 shows more/less thermal lensing effect before/after the exposure time passes tau(th)'s. This means that the thermal lensing effect is more severely reinforced by heating and stabilized by thermal diffusivity in C2H4Cl2 than in C2H4Br2. Notably, the Kerr lensing effect is negligible in this study, although it is noticeable in a Z-scan study with 17 ps laser pulses. (C) 2020 Optical Society of America