- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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High-resolution refractometry using phase shifting interferometry based on spatial light modulator and vortex probe
摘要： We present a spatial light modulator (SLM) based phase shifting interferometry (PSI) using an optical vortex for sensing the refractive index (RI) of liquids. The vortex phase rotates according to the phase shift introduced by a medium, and its rotation angle quantifies the index of refraction of the sample. An interferometer modified with the SLM is designed to obtain reliable results. We experimentally demonstrate the stability of the SLM-based system by measuring interference and phase fluctuation. Experimental results show that the proposed system keeps the fluctuation small. The vortex probe PSI combined with the SLM-based interferometer enables not only detecting extremely small changes in concentration but also precisely measuring the RI with high resolution of ～10?? refractive index unit.
关键词： Refractive index sensing,Spatial light modulator,Optical vortex,Interferometry
更新于2025-09-23 15:22:29
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Vortex beam generation with variable topological charge based on a spiral slit
摘要： We propose a vortex beam generator based on a nanometer spiral slit and explore the propagation rule of the topological charge. Compared to the common methods of generation of a vortex beam with a fixed topological charge, the optical vortex generated by the proposed vortex beam generator has the topological charge varying with the propagation distance. The value of topological charge can be modulated by the geometric charge of the spiral slit and the propagation distance. Theoretical analysis predicts the variation rule of the topological charge of vortex beam in the near field, and numerical simulations and experimental measurement verify the proposed scheme. Discussion on the shape and structure of the spiral slit is also presented. This work provides the theoretical foundation for the generation of a vortex field with variable topological charge. The simple geometry of the vortex beam generator and the flexible modulation of the topological charge must inspire applications of the vortex beam.
关键词： optical vortex,near-field diffraction,variable topological charge
更新于2025-09-23 15:22:29
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All-fiber short-pulse vortex laser with adjustable pulse width
摘要： A laser with short pulse width and direct output of a vortex beam was reported herein. This laser was fabricated from a nonlinear loop mirror (NOLM) and a coupler composed of a single mode fiber and few-mode fiber fused together. The NOLM is responsible for generating pulses, and the coupler acts as a beam splitter and mode converter. Two stable vortex modes can be formed by adjusting the polarization controller, whose pulse widths are 1.098 ps and 542 fs, respectively.
关键词： optical vortex,fiber lasers,mode-locked laser
更新于2025-09-23 15:21:01
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External pressure induced liquid crystal defects for optical vortex generation
摘要： Simple and arbitrary creation of liquid crystal (LC) defects can be highly useful, in particular, for the creation of optical vortex. We report a novel method to create an isolated and stable +1 type concentric LC defect by combing an external pressure on a vertically aligned liquid crystal cell (VALC) and the application of electric fields. The method does not require special material in alignment layer, nor patterned electrodes such as in spatial light modulator, but it can produce stable and rewritable defects in a LC cell. We show that the created +1 defect can be used to generate optical vortices with ±2(cid:125) orbital angular momentum. The simple and cost-effective process and its tunability for the position of defect make the method useful in various applications such as advanced optical communication and quantum computation using tunable optical vortices.
关键词： electric fields,orbital angular momentum,liquid crystal defects,optical vortex generation,external pressure
更新于2025-09-23 15:21:01
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Selection of the confining beam for laser direct writing with scanning absorbance modulation
摘要： Absorbance-modulation optical lithography has been proposed to obtain super-resolution grating patterns with far-field optics. However, the patterns are monotonous since the interference fringes are used as the confining beam. We propose laser direct writing with scanning absorbance modulation to produce free super-resolution patterns. Four kinds of optical vortex beams are studied as the confining beam and the performance of scanning absorbance modulation using each of them is simulated. In conclusion, the selection of the best confining beam has to follow three criteria and an example is the 2-level, 1.5-order optical vortex beam.
关键词： laser direct writing,optical vortex beam,absorbance modulation
更新于2025-09-23 15:19:57
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Radial-profile-customized orbital-angular-momentum modes: Featuring tailored Gaussian intensity pattern at target receiving plane
摘要： We present the modified-Bessel-superposed Gaussian (MBSG) orbital-angular-momentum (OAM) modes, which can evolve into a field featuring a tailored Gaussian amplitude profile after propagating to a target receiving plane. Analytical expressions for the MBSG OAM modes at a source plane are developed in both the space and wavevector domains. The space- and wavevector-domain representations of the MBSG OAM modes at the source plane are found to share a mathematically formal similarity. We propose to utilize this appealing property for designing a Fourier-transform-based approach to forming the MBSG OAM modes at the source plane. Unlike other commonly reported OAM modes, the receiving-plane field of MBSG OAM modes always exhibits a customized non-ring-shaped Gaussian intensity pattern. This behavior can be exploited, e.g., to benefit the projective phase-flattening OAM measurement and to reduce the turbulence-induced OAM-mode scattering in relevant practical applications.
关键词： Fourier transform,Orbital angular momentum,Optical vortex,Spiral phase front
更新于2025-09-19 17:15:36
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Direct femtosecond laser surface structuring with complex light beams generated by q-plates
摘要： Direct femtosecond (fs) laser surface structuring became a versatile way to generate surface structures on solid targets demonstrating a high degree of flexibility and controllability in creating different types of structures for many applications. This approach demonstrated an alteration in various properties of the surface, such as optical properties, wetting response, etc. This paper focuses on direct fs laser surface structuring using complex light beams with spatially variant distribution of the polarization and fluence, with emphasis on the results obtained by the authors by exploiting q-plate beam converters. Although striking scientific findings were achieved so far, direct fs laser processing with complex light fields is still a novel research field, and new exciting findings are likely to appear on its horizon.
关键词： femtosecond laser surface processing,LIPSS,vector vortex beams,optical vortex
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Toroidal and reverse flux of light in the sharp focus
摘要： We obtain a set of explicit analytical expressions that completely describe a light field with a double higher-order singularity (phase and polarization), as well as distributions of its intensity and energy flux near the focus.There is a reverse energy flux on the optical axis near the focus, which is comparable in magnitude with the forward flux. There is a toroidal energy flux in the focal area near the dark rings in the distribution of the longitudinal component of the Poynting vector.
关键词： cylindrical vector beam,optical vortex,energy backflow,toroidal vortex,tight focusing
更新于2025-09-19 17:13:59
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Kummer laser beams with a transverse complex shift
摘要： Here, we study asymmetric Kummer beams, whose complex amplitude is proportional to the Kummer function (a degenerate hypergeometric function). These beams are exact solutions of the paraxial equation (Schr?dinger-type equation) and are obtained from the conventional symmetric hypergeometric beams by complex shift of the transverse coordinates. On propagation, the asymmetric Kummer beams change their intensity weakly and rotate around the optical axis. These beams are an example of vortex laser beams with a fractional orbital angular momentum (OAM), which depends on four parameters: the vortex topological charge, the shift magnitude, the logarithmic axicon parameter, and the degree of the radial factor. Changing these parameters, it is possible to control the beam OAM, continuously increasing or decreasing it.
关键词： asymmetric laser beam,orbital angular momentum,optical vortex,logarithmical axicon,Kummer function,hypergeometric function
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Terahertz Wave Generation in Air by Femtosecond Optical Vortex Pulses
摘要： Terahertz (THz) radiation is of great current interest due to many applications such as nonlinear THz spectroscopy and imaging. One of the compact and effective methods to obtain very high THz field strengths and extremely broadband spectral widths is THz wave generation from plasma filaments formed in air by focused bichromatic femtosecond laser pulses consisting of the first and the second harmonics (FH, SH). Here we investigate the effect of an azimuthal phase modulation of the SH carrying an optical vortex charge on the intensity and phase distribution of the THz pulse emitted from the laser induced plasma filament in air. We present both experimental and theoretical results.
关键词： Terahertz radiation,plasma filaments,femtosecond optical vortex pulses,bichromatic femtosecond laser pulses
更新于2025-09-11 14:15:04