Off Resonant Laser Induced Ring Emission

А. П. Войтович, О. Е. Костик, В. В. Машко

An experimental investigation was made of the spectral and energy characteristics of the radiation emitted by a dye laser with a ring resonator containing an absorbing medium (potassium vapor) in which an anisotropy was induced by a strong external optical wave. Narrowing of the dye output radiation to about 10???2 nm and locking of the emission spectrum to one- and two-photon absorption lines of the potassium vapor were observed. An investigation was made of the locking efficiency for different polarizations of the strong wave.

Davıd L. Andrews, David S. Bradshaw

Noriaki Horiuchi

Won-Kyu Lee, Young-Chul Noh, Jin-Ho Jeon +4 more

We studied the conical emission in samarium (Sm) vapor under the near-resonant condition. The incident dye laser was tuned to the transition line, 4f66s2 7F→4f6(7F)6s6p(1P0)(λ=562.601 nm), of the Sm atom. Using a high-temperature oven, we could obtain the atomic density of 8×1014 atoms/cm3, 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.

Stefano Longhi, P. Laporta

Field confinement in a microchip laser with transversely varying gain and plane–plane cavity mirrors is theoretically discussed with a semiclassical treatment. We show that the common notion of a transverse cavity mode becomes closely linked to that of a longitudinal cavity mode owing to the key role that detuning of the longitudinal cavity frequency from the atomic resonance plays in the formation of the transverse field profile. In particular, we show that as the pump size decreases the laser emission is pulled toward the atomic resonance frequency on the negative detuning side. Strong mode pulling is interpreted as being due to the index-antiguiding effect induced by the pump and manifests itself as a ring pattern in the far-field spatial intensity.

M. M-Tehrani, L. Mandeļ