Optical harmonic generation in media with positive dispersion

Third-harmonic generation in gaseous media with positive dispersion is investigated. Using the example of the 351.7–117.2 nm conversion process in rare gases the possibility of optical harmonic generation in media with positive dispersion was first experimentally obtained and theoretically substantiated. Unusual dependence of the thirdharmonic generation efficiency on the intensity of incident beam (W ⁴) is explained due to the second-order Kerr effect.