We derive an explicit analytical relationship to describe the axial light intensity when a Gaussian beam is diffracted by the logarithmic axicon (LA). An evaluation formula for the effective radius of the diffraction pattern that we deduce shows the said radius to be in inverse proportion to the LA "force" parameter. The finite-difference time-domain-based simulation has shown that using the LA makes it possible to go beyond the diffraction limit: in the LA vicinity, the FWHM of the light beam can be as small as one fifth of the illumination wavelength.
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http://dx.doi.org/10.1364/JOSAA.28.000844 | DOI Listing |
This study explores the propagation dynamics of Bessel-Gaussian (BG) beams, focusing on vortex-splitting behavior under short-range atmospheric conditions with varying disturbances. Using the split-step beam propagation method, the research reveals that greater atmospheric turbulence and longer transmission distances enhance both the average vortex splitting distance and its variance while reducing the average topological charge of the received OAM mode. Conversely, laminar conditions promote beam stability.
View Article and Find Full Text PDFA reconfigurable holographic metasurface (HM) with multifunctional modulation of radiation and scattering for conformal applications is designed in this paper. Based on optical holography theory, a holographic conformal modulation mechanism is proposed, and the conformal surface impedance distribution of HM is derived. To illustrate this mechanism, the designed conformal reconfigurable HM is used to demonstrate a series of radiation and scattering modulation functions, with its reconfigurable property enabling dynamic beam control.
View Article and Find Full Text PDFThe controlled visible spatial modes and vortex beams with tunable properties are highly sought after in cutting-edge applications, such as optical communication. In this study, by utilizing a hybrid pumping scheme, we demonstrate an ultra-compact, 607 nm orbital Poincaré laser based on a diode-pumped Pr:YLF laser. The system can generate various structured modes, including Laguerre-Gaussian (LG), Hermite-Gaussian (HG), and Hermite-Laguerre-Gaussian (HLG), all of which are mapped onto a first-order orbital Poincaré sphere.
View Article and Find Full Text PDFScintillation restricts the development of free space optical communication in near-space hypersonic vehicles. We derived analytical formulae for the on-axis scintillation index of a partially coherent flat-topped beam in a bidirectional turbulent atmosphere and plasma link based on the Collins formula. The numerical results indicate that over long-distance propagation ranges, the on-axis scintillation index of a partially coherent flat-topped beam in bidirectional transmission is smaller than that of a Gaussian Schell model beam under the same conditions.
View Article and Find Full Text PDFIn this paper, the focusing and tight-focusing properties of radially polarized (RP) Bessel-Gaussian (BG) rotationally-symmetric power-exponent-phase vortex beam (RPVBs) were investigated theoretically and experimentally. Based on the theory of vector beam, the propagation and tight-focusing models were derived to reveal the focusing and tight-focusing properties of the RP-BG-RPVBs by numerical simulation. Then, the experimental setup was established to validate that the RP-BG-RPVBs presented the fan-shaped and polycyclic intensity distribution, which possessed the features of RP beams, BG beams, and RPVBs, similarly.
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