Efficient generation of annular cylindrical vector beams by refractive axicons with high-transmission thin-film retarders

Sedukhin, Andrey G.

doi:10.1016/j.optcom.2021.127293

Cited by 3 publications

(3 citation statements)

References 51 publications

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“…Methods for generating CVBs can be divided into in-cavity and outcavity strategies. In in-cavity methods, some special optical elements are directly added to the laser cavity to produce radial or angular polarized beams [21][22][23][24][25][26][27][28][29][30]. Out-cavity methods use some auxiliary devices to correct the polarization distribution to spatially uniformly polarized beams [31][32][33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Generation of various vortex beams based on transformation materials

Lai

Dong

2023

J. Opt.

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A flexible vortex beam generator (VBG) is proposed based on transformation optics (TO) to convert input plane waves to various output vortex beams. The methodology is a geometrical one that is based on the topological equivalence between the vortex beam cross section disc and a belt, turning the in-plane curvilinear distributed phase or polarization structures in the disc to be redistributed around the belt. Consequently, abundant vortex beams can be exported by simply configuring the incidence angles and polarization directions of the plane waves. The topology and wave propagation characteristics behind the system are investigated, and TO is used to obtain the desired materials by adopting a specific space mapping. Some sample numerical simulations are described to verify the feasibility of the proposed design, including several complex orbital angular momentum and cylindrical vector beams. Due to its flexibility and simplicity, the proposed VBG likely has extensive application prospects.

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Section: Introductionmentioning

confidence: 99%

Generation of various vortex beams based on transformation materials

Lai

Dong

2023

J. Opt.

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“…The conventional lenses typically exhibit spherical or cylindrical curvature forms, whereas the axicon lenses feature a conical-shaped focusing surface. When employing an axicon lens, a Gaussian profile beam is transformed into a converging beam with a transverse profile that comprises a sharp central core surrounded by several rings with varying brightness [5,6]. The most intense part of the central core keeps the shape and size during propagation, forming a non-diffractive zone.…”

Section: Introductionmentioning

confidence: 99%

Non-Paraxial Effects in the Laser Beams Sharply Focused to Skin Revealed by Unidirectional Helmholtz Equation Approximation

2023

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Laser beams converging at significant focusing angles have diverse applications, including quartz-enhanced photoacoustic spectroscopy, high spatial resolution imaging, and profilometry. Due to the limited applicability of the paraxial approximation, which is valid solely for smooth focusing scenarios, numerical modeling becomes necessary to achieve optimal parameter optimization for imaging diagnostic systems that utilize converged laser beams. We introduce a novel methodology for the modeling of laser beams sharply focused on the turbid tissue-like scattering medium by employing the unidirectional Helmholtz equation approximation. The suggested modeling approach takes into account the intricate structure of biological tissues, showcasing its ability to effectively simulate a wide variety of random multi-layered media resembling tissue. By applying this methodology to the Gaussian-shaped laser beam with a parabolic wavefront, the prediction reveals the presence of two hotspots near the focus area. The close-to-maximal intensity hotspot area has a longitudinal size of about 3–5 μm and a transversal size of about 1–2 μm. These values are suitable for estimating spatial resolution in tissue imaging when employing sharply focused laser beams. The simulation also predicts a close-to-maximal intensity hotspot area with approximately 1 μm transversal and longitudinal sizes located just behind the focus distance for Bessel-shaped laser beams with a parabolic wavefront. The results of the simulation suggest that optical imaging methods utilizing laser beams with a wavefront produced by an axicon lens would exhibit a limited spatial resolution. The wavelength employed in the modeling studies to evaluate the sizes of the focus spot is selected within a range typical for optical coherence tomography, offering insights into the limitation of spatial resolution. The key advantage of the unidirectional Helmholtz equation approximation approach over the paraxial approximation lies in its capability to simulate the propagation of a laser beam with a non-parabolic wavefront.

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“…В части новых устройств для совершенствования прямой сверхразрешающей лазерной записи дифракционных структур, а также улучшения энергетики и качества пучков на входе высокоапертурных объективов записи, с сокращением размеров сфокусированного лазерного пятна, был предложен и исследован новый вид гибридных оптических систем, объединяющих в себе светоэффективный тонкопленочный конвертер поляризации лазерного пучка из линейной формы в радиальную и преобразователь формы пучка из однородной дисковой в кольцевую [3]. Энергетическая эффективность преобразования интенсивности и поляризации лазерного пучка в такой системе приближается к 100%.…”

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