We studied the conical emission in samarium (Sm) vapor under the near-resonant condition. The incident dye laser was tuned to the transition line, 4f<sup>6</sup>6s<sup>2</sup> <sup>7</sup>F→4f<sup>6</sup>(<sup>7</sup>F)6s6p(<sup>1</sup>P<sup>0</sup>) (λ=562.601 nm), of the Sm atom. Using a high-temperature oven, we could obtain the atomic density of 8×10<sup>14</sup> atoms/cm<sup>3</sup>, large enough to observe the conical emission. We observed one to three rings around the original laser beam, and the number of the rings depended on the laser intensity, the laser wavelength, and the atomic density. These results are attributed to the self-phase modulation of the laser beam interacting with the near-resonant atomic medium. We give a simple expression that describes the dependence of the locations of the rings on the laser intensity. We compare the experimental results with this expression quantitatively and then estimate the nonlinear susceptibility of Sm vapor.
© 2001 Optical Society of America
(190.4420) Nonlinear optics : Nonlinear optics, transverse effects in
(190.5940) Nonlinear optics : Self-action effects
(300.6210) Spectroscopy : Spectroscopy, atomic
(300.6380) Spectroscopy : Spectroscopy, modulation
(300.6420) Spectroscopy : Spectroscopy, nonlinear
Won-Kyu Lee, Young-Chul Noh, Jin-Ho Jeon, Jai-Hyung Lee, Joon-Sung Chang, Kwang-Hoon Ko, and Jongmin Lee, "Conical emission as a result of self-phase modulation in samarium vapor under the near-resonant condition," J. Opt. Soc. Am. B 18, 101-105 (2001)