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 (χ(2)). Surprisingly, even at 0 V, a non-EFISH bulk χ(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 χ(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 χ(2)zzz = 0.22 pm/V at 0 V is ascertained. Adding a dc-electric field during the EFISH-measurements the χ(2) rises and reaches a maximum value of χ(2)zzz = 13,5 pm/V at the electric breakdown field strength of 102 MV/m. This EFISH-enhanced χ(2)zzz-value surpasses the χ(2) main components of traditional nonlinear crystals, such as KDP, LBO or BBO significantly. This and a high intrinsic third order susceptibility of χ(3) ≈ 5x10-20 makes arsenic sulfide an interesting material for nonlinear hybrid photonic applications.