A study on the optical non-linearity near the band gap energy region of CuCl by the non-degenerate reflected four-wave mixing

We have demonstrated three beam non-degenerate reflected four-wave mixing (reflected FWM) in which two driving fields have the same photon energy (?ω₁) and the monitor and the resulting mixed light fields have another equal photon energy (?ω₂). Mixed light has been observed with the driving field's energy from Z₃ exciton up to band gap energy when ?ω₂ is fixed in the Z₃ and Z_1,2 exciton resonance region. The mechanism by which such non-degenerate optical non-linearity occurs is discussed according to a calculation by a simple model.