https://doi.org/10.1140/epjp/s13360-025-06506-7
Regular Article
A new mechanism of off-axis helical phase engineering in spatial four-wave-mixing light at frequency up-conversion regime
1
Department of Physics, Sree Chaitanya College, Habra (WB State University), 743268, North 24 Parganas, W. B., India
2
Department of Physics & Research Centre in Natural Sciences, Prabhat Kumar College, Contai (Vidyasagar University), 721401, Purba Medinipur, W. B., India
3
Institute of Astronomy Space and Earth Science, 700059, Kolkata, W. B., India
a
pradipta@pkcollegecontai.ac.in
Received:
31
December
2024
Accepted:
1
June
2025
Published online:
19
June
2025
A scheme is proposed for the evolution of the helical phase with off-axis vortices in spatial four-wave-mixing (FWM) light generated in a coherent four-level ladder-type atomic medium at the frequency up-conversion regime. The control field coupling the uppermost transition of three-photon transition channel within the FWM-loop of the atomic model is taken as a vortex beam (Laguerre-Gaussian (LG) beam), which gives rise to the appearance of vortex FWM field due to optical angular momentum (OAM) transfer from this vortex control field. If the vortex control field is accompanied by a weak plane-wave field of constant Rabi frequency, the appearance of dual off-axis vortices is noticed in the helical phase pattern of the FWM field at both the resonant and nonresonant detuning of strong control fields operating in the system. It is surprising to mention here that this coherent phenomenon occurs without invoking any additional LG beam to the vortex control field. We have shown that the spatial extent of spreading out of vortices from the central position of the helical phase pattern is almost proportional to the value of the Rabi frequency of the applied plane wave-field. If the plane wave is replaced by a Gaussian wave, off-axis vortices are observed to be still present in the helical phase profile with non-dual character. The present study on structuring vortex FWM light belongs to the ultraslow propagation regime. Thus, the work may be important for its future application in quantum information science and technology governed by OAM-based nonlinear photonics.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
