Dispersion of |χ14(2)(ω1+ω2)| in GaAs and GaSb and of |χ14(2)(2ω)| in GaP in the optical region

The second-harmonic optical nonlinear susceptibility |χ14(2)(2ω1) | of GaP and the sum-frequency nonlinear susceptibility |χ14(2) (ω1+ω2)| of GaAs and GaSb were measured by the reflected-harmonic method. The sources were a tunable dye laser in the energy range 1.2≤ ω1≤1.68 eV, while ω2=1.78 eV. Large dispersion of the nonlinear susceptibility was found in the vicinity of the E1 transition energy in GaP. The spectra of |χ14(2)(ω1+ω2)| and Miller's coefficient δ(ω1+ω2) in GaAs and GaSb were found to be similar to the same quantities in a second-harmonic-generation experiment. The nonlinear susceptibilities were also calculated using a simplified model proposed by Bell.