Work

Resonant nonlinear refraction of 4–5−μm light in CO and CO2 gas

Year: 2021

Type: article

Abstract: The resonant nonlinear refraction of $4\text{--}5\text{\ensuremath{-}}\ensuremath{\mu}\text{m}$ light in CO and $\mathrm{C}{\mathrm{O}}_{2}$ gas at a peak intensity of $15\phantom{\rule{0.16em}{0ex}}\mathrm{MW}/\mathrm{c}{\mathrm{m}}^{2}$ was demonstrated using time- and frequency-resolved measurements of self-focusing and self-defocusing. The nonlinearity of these molecular gases exhibits intensity-dependent sign reversals and a $<4\text{\ensuremath{-}}\mathrm{ns}$ response time. A change from self-focusing to self-defocusing or vice versa was observed to occur for Rabi frequencies that are comparable to the collisional linewidth. A density matrix model for the nonlinear susceptibility of a strongly driven two-level system provides a qualitative explanation for these results.

Source: Physical Review A

DOI: 10.1103/physreva.104.043519