Measurement of the Third-Order Nonlinear Optical Susceptibility \(\chi^{(3)}\) for the \(1002-cm^{-1}\) Mode of Benzenethiol Using Coherent Anti-Stokes Raman Scattering with Continuous-Wave Diode Lasers

Abstract

The components of the third-order nonlinear optical susceptibility (\chi^{(3)}) for the (1002-cm^{–1}) mode of neat benzenethiol have been measured using coherent anti-Stokes Raman scattering with continuous-wave diode pump and Stokes lasers at 785.0 and 852.0 nm, respectively. Values of (2.8 ± 0.3 × 10^{–12}), (2.0 ± 0.2 × 10^{–12}), and (0.8 ± 0.1 × 10^{–12} cm g^{–1} s^2) were measured for the xxxx, xxyy, and xyyx components of (|3\chi^{(3)}|), respectively. We have calculated these quantities using a microscopic model, reproducing the same qualitative trend. The Raman cross-section (\sigma_{RS}) for the (1002-cm^{–1}) mode of neat benzenethiol has been determined to be (3.1 ± 0.6 × 10^{–29} cm^2) per molecule. The polarization of the anti-Stokes Raman scattering was found to be parallel to that of the pump laser, which implies negligible depolarization. The Raman linewidth (full-width at half-maximum) (\Gamma) was determined to be (2.4 ± 0.3 cm^{–1}) using normal Stokes Raman scattering. The measured values of (\sigma_{RS}) and (\Gamma) yield a value of (2.1 ± 0.4 × 10^{–12} cm g^{–1} s^2) for the resonant component of (3χ^{(3)}). A value of (1.9 ± 0.9 × 10^{–12} cm g^{–1} s^2) has been deduced for the nonresonant component of (3\chi^{(3)}).