Phase-induced transparency-mediated structured-beam generation in a closed-loop tripod configuration

Abstract

We present a phase induced transparency based scheme to generate structured beam patterns in a closed four level atomic system. We employ phase structured probe beam and a transverse magnetic field (TMF) to create phase dependent medium susceptibility. We show that such phase dependent modulation of absorption holds the key to formation of a structured beam. We use a full density matrix formalism to explain the experiments of Radwell et al. [Phys. Rev. Lett. 114, 123603 (2015)] at weak probe limits. Our numerical results on beam propagation confirms that the phase information present in the absorption profile gets encoded on the spatial probe envelope which creates petal-like structures even in the strong field limit. The contrast of the formed structured beam can be enhanced by changing the strength of TMF as well as of the probe intensity. In weak field limits an absorption profile is solely responsible for creating a structured beam, whereas in the strong probe regime, both dispersion and absorption profiles facilitate the generation of high contrast structured beam. Furthermore we find the rotation of structured beams owing to strong field induced nonlinear magneto-optical rotation (NMOR).

Complete energy conversion between light beams carrying orbital angular momentum using coherent population trapping for a coherently driven double- Λ atom-light-coupling scheme

“…As one can see from Eq. (34), in this case the same vorticity of the first vortex beam Ω p1 (z i ) is transferred to the second generated field Ω p2 (z).…”

“…The phase singularity at the beam core of the twisted beam renders its donut-shaped intensity profile. A number of interesting effects appear when this type of optical beams interact with the atomic systems [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Among them optical vorticities of slow light [35,39,40,42,44] have caused a considerable interest, as the OAM brings a new degree of freedom in manipulation of the optical information during the storage and retrieval of the slow light [45,46].…”

Vectorial light-matter interaction -- exploring spatially structured complex light fields

“…The atoms are pumped into spatially varying atomic dark states, leading to an angular variation of the opacity of the medium. The interaction allows coupling between an external magnetic field and a polarization structured optical field via the atomic spin alignment, 173 where the atomic transparency is set by the angle between the local polarization direction and the external magnetic field direction 174,175 as shown in Fig. 4.…”

Controlling Dispersion Characteristic of Focused Vortex Beam Generation

“…Structured beams have unique amplitude, phase, and polarization distributions, which are extensively used in many fields and attract a lot of attention [1][2][3][4]. As an important structured beam, the vortex beam has a helical wavefront with a phase singularity in the center.…”