Voltage-Controllable Second-Order Susceptibility in Arsenic Sulfide Film

Electric field induced second harmonic (EFISH) generation on arsenic sulfide films deposited via thermal evaporation is investigated, demonstrating a strong voltage-controllable second-order optical susceptibility ( \({\chi }^{(2)}\) ). Surprisingly, even at 0 V, a non-EFISH bulk \({\chi }^{(2)}\) is also revealed. Supplementary polarization- and angle-dependent SHG measurements on as-deposited films show Maker fringe patterns from which the components of the \({\chi }^{(2)}\) tensor are determined. Calibrating the observed second harmonic generation (SHG) intensity from the arsenic sulfide against the SHG from a classic beta barium borate (BBO) crystal, a main component of \({\chi }_{zzz}^{(2)}\) = 0.22 pm/V at 0 V is ascertained. Adding a dc-electric field during the EFISH-measurements the \({\chi }^{(2)}\) rises and reaches a maximum value of \({\chi }_{zzz}^{(2)}\) = 13,5 pm/V at the electric breakdown field strength of 102 MV/m. This EFISH-enhanced \({\chi }_{zzz}^{(2)}\) -value surpasses the \({\chi }^{(2)}\) main components of traditional nonlinear crystals, such as KDP, LBO or BBO significantly. This and a high intrinsic third order susceptibility of \({\chi }^{(3)}\approx 5{\times 10}^{-20}\frac{{\text{m}}^{2}}{{\text{V}}^{2}}\) makes arsenic sulfide an interesting material for nonlinear hybrid photonic applications.