Beam shape modification due to the non-linear optical response in a dense rubidium vapor

Dense atomic vapors have strong non-linear optical properties for near-resonant light. As a result, an initially Gaussian beam profile is strongly distorted due to propagation through such a dense vapor, leading to various distinct beam profiles. In our experiment, we track the detuning from resonance at which these beam profiles occur as a function of intensity. We establish a detuning curve as a function of intensity for each shape at two different cell temperatures. After proper scaling, the detuning curves all collapse onto one universal detuning curve, which suggests that the shapes are manifestations of the same underlying phenomenon.