van der Waals interaction–induced reverse saturable absorption in Rydberg atoms

The influence of van der Waals (vdW) interaction on the nonlinear optical properties of Rydberg atoms is investigated within a three-level cascade scheme established using two probe and control laser fields. It is demonstrated that vdW interaction can induce reverse saturable absorption (RSA) in the Rydberg atoms in the two-photon resonance condition, enabling controllable optical limiting behavior. Furthermore, the presence of vdW interaction facilitates a switch between saturable absorption and RSA and vice versa beyond the two-photon resonance condition, thereby enabling intrinsic optical bistability in the system.