Abstract

A new value of the electronic contribution (the electronic hyperpolarizabiiity) to the third-order nonlinear susceptibility of gaseous H2 has been determined. A phase-modulated version of stimulated Raman (gain/loss) spectroscopy¹, is employed for these measurements. A phase-modulated signal wave is generated at the probe frequency by use of two orthogonally polarized phase-modulated pump waves. With this technique a signal linearly proportional to either the real or imaginary part of the third-order susceptibility can be selected. Highresolution (10-yHz) GW laser sources are used in these measurements.

© 1985 Optical Society of America