Azimuthally dependent absorption and gain in an atomic system with spontaneously generated coherence controlled by an optical vortex field

This paper examines spatially dependent absorption and gain of a weak probe field in a 3-level atomic Λ-system with spontaneously generated coherence and incoherent pump, using an optical vortex beam as the control field. The inhomogeneous phase distribution between the probe and vortex fields modulates the transverse distribution of the system's optical response. A flexible control over the azimuthal modulation in the transverse plane can be achieved by changing such parameters as the orbital angular momentum and the optical transition detuning. The vortex parameters can also be used to affect the population distribution of the atomic system's upper state. This method for achieving precise control over the optical response characteristics contributes to advances in optical information and communication, quantum devices and sensing.