We investigate the generation of mid-infrared (mid-IR) vortex beams carrying orbital angular momentum (OAM) through nonlinear processes in an inhomogeneously broadened 85 Rb atomic ensemble. By employing a four-level atomic system featuring two strong control fields and a weak probe field, we generate a non-degenerate four-wave mixing signal at a wavelength of 5.23 µm. Applying the density-matrix formalism, we derive an analytical expression for the nonlinear atomic coherence which facilitates the transfer of vortex characteristics such as topological charge and intensity and phase profiles from the probe field to the mid-IR signal. Numerical solutions of Maxwell’s wave equation confirm the generation of mid-IR vortex beams with adjustable topological charges and beam widths at different spatial positions. This technique offers significant potential for applications in mid-IR communication, providing additional bandwidth and improved data transmission rates, as well as in fields such as microfluidics, biophysics, and nanotechnology, where OAM-carrying beams can manipulate microparticles with precision.
We investigate the generation of mid-infrared (mid-IR) vortex beams carrying orbital angular momentum (OAM) through nonlinear processes in an inhomogeneously broadened 85 Rb atomic ensemble. By employing a four-level atomic system featuring two strong control fields and a weak probe field, we generate a non-degenerate four-wave mixing signal at a wavelength of 5.23 µm. Applying the density-matrix formalism, we derive an analytical expression for the nonlinear atomic coherence which facilitates the transfer of vortex characteristics such as topological charge and intensity and phase profiles from the probe field to the mid-IR signal. Numerical solutions of Maxwell’s wave equation confirm the generation of mid-IR vortex beams with adjustable topological charges and beam widths at different spatial positions. This technique offers significant potential for applications in mid-IR communication, providing additional bandwidth and improved data transmission rates, as well as in fields such as microfluidics, biophysics, and nanotechnology, where OAM-carrying beams can manipulate microparticles with precision.
We explore the generation of orbital angular momentum (OAM) carrying mid-infrared Bessel-Gaussian beams through nonlinear interactions within a non-uniformly broadened 85 Rb atomic ensemble. Utilizing an efficient four-wave mixing (FWM) scheme driven by two strong control fields and a weak probe field, we achieve coherent emission at a wavelength of 5.23 µm. By employing the density matrix approach, we obtain an analytical expression for the nonlinear atomic coherence involved in the four-wave mixing process, elucidating how the Bessel-Gaussian profile of the probe field is transferred into the mid-infrared signal. Numerical simulations of Maxwell’s wave equation ensure the generation of phase-matched, non-diffracting Bessel-Gaussian beams, which can be precisely controlled by manipulating the spatial susceptibility of the atomic medium. Furthermore, this study demonstrates the potential of higher-order Bessel-Gaussian beams with OAM to significantly advance applications in high-speed communication, biomedical imaging, and optical manipulation, owing to their robust beam integrity and enhanced data transmission capabilities in the mid-infrared spectrum.
This paper investigates the potential of nonlinear processes in an inhomogeneously broadened atomic ensemble to generate an Airy beam in the mid-IR regime. We concentrate on a four-level 85 Rb atomic system that interacts nonlinearly with two strong control fields and a weak probe field. This interaction results in a non-degenerate four-wave mixing (FWM) signal at a wavelength of 5.23 µm, facilitating the transfer of Airy features from the probe field to the mid-IR FWM signal. Using computational methods, we numerically solve Maxwell’s wave equation in the paraxial limit, demonstrating the successful transfer of Airy beam-induced spatial inhomogeneity from atomic coherence to the generated mid-IR signal. We show the generation of a finite-energy mid-IR Airy beam through the nonlinear FWM process, with transverse intensity variations observed at different propagation lengths, offering enhanced visualization of the Airy beam’s evolution. The generation and manipulation of the Airy beam provides significant advantages for imaging, sensing, spectroscopy, and optical communications. Their self-healing properties and ability to preserve beam integrity over long distances enhance precision, resolution, and reliability, making them ideal for various mid-IR applications.
Abstract This study presents a theoretical exploration of generating 420 nm Bessel-Gaussian beam with orbital angular momentum (OAM) via nonlinear processes in a four-level 85 Rb atomic system. A non-degenerate four-wave mixing (FWM) configuration, driven by two strong control fields at wavelengths 780 nm and 776 nm along with a weak field, enables the generation of the desired blue Bessel-Gaussian beam. Our analysis examines how the Bessel-Gaussian properties of the initial beams including intensity, phase profiles, and topological charges are transferred into the generated 420 nm beam at specific transverse positions. Using Maxwell’s wave equations, we explicitly explore how these spatial profiles evolve with varying topological charges over different propagation distances, providing deeper insights into Bessel-Gaussian information transfer mechanisms. The generation and characterization of 420 nm structured beam highlight promising applications, particularly in the precise manipulation of microparticles, due to their enhanced resolution and superior trapping abilities. This comprehensive theoretical framework establishes a foundation for future experimental and applied research in optical manipulation and high-resolution imaging.
We theoretically study the generation of orbital angular momentum (OAM) based on the four-wave mixing process in a diamond-type homogeneously broadened 85 R b atomic system. We use density matrix formalism at a weak field limit to explain the origin of vortex translation between different optical fields and a generated signal. We show how the singularities, which are omnipresent in the phases of the input optical vortex beams, can be profoundly mapped to atomic coherence in the transverse plane, which holds the origin of OAM translation. This translation process works well even for a moderately intense probe and control field, which enhances medium nonlinearity. The generation and manipulation of OAM of the light beam in a nonlinear medium may have important applications in optical tweezers and quantum information processing systems.
We theoretically investigate coherent orbital-angular-momentum (OAM) transfer and dispersion-controlled light propagation in a ladder-type Er YAG three-level system. Using the density-matrix formalism and coupled Maxwell-Bloch equations, we derive analytical expressions for the probe and generated beams that explicitly incorporate Er ion concentration. We show that an incident vortex-carrying probe beam transfers its OAM to a generated signal beam through a concentration-dependent sum-frequency nonlinear process, with complete phase and topological-charge preservation. By analyzing conversion efficiency, spatial phase, and intensity distributions, we identify an optimal Er concentration (3 percent) that maximizes vortex-transfer efficiency. Furthermore, the absorption and dispersion spectra of the probe and generated beams reveal the mechanism underpinning the vortex transfer and demonstrate tunable transitions between fast and slow regimes. These results establish Er YAG as a viable solid-state platform for the coherent manipulation of structured light, enabling efficient vortex-beam frequency conversion and dispersion engineering for applications in high-dimensional quantum communication, wavelength-compatible OAM interfaces, and slow-light photonic signal processing.
We investigate coherent orbital-angular-momentum (OAM) transfer and dispersion-controlled light propagation in a ladder-type Er³⁺: YAG three-level system. Using the density-matrix formalism and coupled Maxwell-Bloch equations, we derive analytical expressions for the probe and generated beams that explicitly incorporate Er³⁺-ion concentration. We show that an incident vortex-carrying probe beam transfers its OAM to a generated signal beam through a concentration-dependent sum-frequency nonlinear process, with complete phase and topological-charge preservation. By analyzing conversion efficiency, spatial phase, and intensity distributions, we identify an optimal Er³⁺ concentration (3%) that maximizes vortex-transfer efficiency. Furthermore, the absorption and dispersion spectra of the probe and generated beams reveal the mechanism underpinning the vortex transfer and indicate the potential for concentration-selectable transitions between fast and slow propagation regimes. These results establish Er³⁺: YAG as a viable solid-state platform for coherent manipulation of structured light, enabling efficient vortex-beam frequency conversion and dispersion engineering, with potential relevance to classical and quantum OAM-based communication protocols, wavelength-compatible OAM interfaces, and slow-light photonic signal processing.