Non-contact control of two-photon absorption.

In this experimental work, we address the issue of the control of two-photon absorption in a Doppler broadened medium of Rb85 atoms under the ladder level coupling 5S→5P→5D. Here, suppression and enhancement of two-photon absorption are executed by applying an auxiliary laser beam, which is not physically propagating in the same line of the pump-probe combination. Instead, the auxiliary beam, which is in resonance with the Rb85 D transition, is at a finite distance from the line of propagation of the pump-probe combination.