INDEXES GOVERNING OPTICAL SELF-FOCUSING AND SELF-INDUCED CHANGES IN THE STATE OF POLARIZATION IN N-2, O-2, H-2, AND AR GASES

We employ recently published data on the dc Kerr effect and electric-field-induced second-harmonic generation in N2, O2, H2, and Ar gases to calculate the nonlinear-optical indices governing self-focusing, self-induced changes in the state of polarization, and third-harmonic generation, over a wide range of wavelengths in these gases. We construct a new, one-parameter, dispersion formula that not only fits all existing data on the above gases, but also fits recent quantum calculations of each tensor component of the third-order optical susceptibility of helium, over a wide range of frequency arguments. We compare the difference between the predictions of this formula and the predictions of a previously used formula based only on linear refractive-index dispersion. The difference is negligible at 1053 nm but becomes significant at blue or shorter wavelengths (<350 nm), where it indicates the uncertainty in our dispersion calculations. We find the coefficient for self-induced polarization changes in one atmosphere of air to be c1221(-,-) =(242)×10-19 esu, at 1053 nm and 20°C. This is consistent with one of two reported measurements of this coefficient. © 1990 The American Physical Society.