Abstract: Anew kind of second order nonlinear optical(NLO) material——m-hydroxybenzoic acid(HBA) was reported in this paper. Primary study results revealed that it had a relatively strong nonlinearity, its powder SHG effect was 12 times that of KDP. The solid cut-off wavelength K_cut-off (350 nm) is very short compared to other organic second order NLOmaterials. The experimental results also showed that HBAhad a high laser damage threshold and good characteristic thermal stability. Furthermore, We calculated its second-order nonlinear hyperpolarizability β and analyzed the microscopic nonlinear properties, and found that the hydroxyl group could improve β obviously while the hydroxyl multisubstitution could hardly contribute to β values.

Key words: m-Hydroxybenzoic acid, Second-order nonlinear optical property, Cut-off wavelength