Modulation of the optical beam with orbital angular momentum in hot atomic rubidium vapor.

The effect of self-focusing and defocusing of the optical beam, which is caused by the interaction between a strong light field and medium, plays an important role in nonlinear optics. The difference in the spatial structure of the strong control beam with orbital angular momentum (OAM) and the Gaussian mode will have different effects on self-focusing and defocusing, which has the potential for realizing the modulation of the self-focusing and the defocusing process of the probe light with OAM. In this work, we report the influence of the spatial structure of the control beam on the self-focusing and defocusing process of the probe beam in a hot rubidium vapor cell with a lambda-type configuration. Under the same experimental condition, the control beam with the Laguerre-Gaussian mode contributes more to self-defocusing, while the Gaussian mode promotes the defocusing effect. The result is promising for manipulating the optical beam with OAM. [ABSTRACT FROM AUTHOR]