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Lei Zhang

Bio: Lei Zhang is an academic researcher from Hangzhou Dianzi University. The author has contributed to research in topics: Paraxial approximation & Gaussian beam. The author has an hindex of 4, co-authored 4 publications receiving 163 citations.

Papers
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Journal ArticleDOI
TL;DR: Based on the generalized diffraction integral formula for treating the propagation of a laser beam through a paraxial misaligned optical system in the cylindrical coordinate system, this paper obtained an analytical formula for a hollow Gaussian beam passing through a Paraxial Misaligned Optical System (POMOS).

60 citations

Journal ArticleDOI
TL;DR: In this paper, a theoretical model is proposed to describe coherent dark hollow beams (DHBs) with rectangular symmetry, and the electric field of a coherent rectangular DHB is expressed as a superposition of a series of series of generators.
Abstract: A theoretical model is proposed to describe coherent dark hollow beams (DHBs) with rectangular symmetry. The electric field of a coherent rectangular DHB is expressed as a superposition of a series ...

58 citations

Journal ArticleDOI
TL;DR: By expanding the hard aperture function into a finite sum of complex Gaussian functions, approximate analytical formulas for a decentered Gaussian beam (DEGB) passing through apertured aligned and misaligned paraxial aperturing paraxian optical systems are derived in terms of a tensor method.
Abstract: By expanding the hard aperture function into a finite sum of complex Gaussian functions, approximate analytical formulas for a decentered Gaussian beam (DEGB) passing through apertured aligned and misaligned paraxial apertured paraxial optical systems are derived in terms of a tensor method. The results obtained by using the approximate analytical expression are in good agreement with those obtained by using the numerical integral calculation. Furthermore, approximate analytical formulas for a decentered elliptical Hermite-Gaussian beam (DEHGB) through apertured paraxial optical systems are derived. As an application example, approximate analytical formulas for a decentered elliptical flattened Gaussian beam through apertured paraxial optical systems are derived. Our results provide a convenient way for studying the propagation and transformation of a DEGB and a DEHGB through apertured paraxial optical systems.

31 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a novel sensor structure composed of a slot microring and a phase-shifted sidewall Bragg gratings in a slot waveguide, which exhibited theoretical sensitivity of 297. 13 nm ∕ RIU, a minimum detection limit of 1. 1 × 1 0 − 4 RIU, the maximum extinction ratio of 20dB, the quality factor of 2 × 10 3 and a compact dimension-theoretical structure of 15 μ m × 8. 5 μ m.

29 citations


Cited by
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Journal ArticleDOI
TL;DR: The numerical results show that the M(2)- factor of a DHB in turbulent atmosphere increases on propagation, which is much different from its invariant properties in free-space, and is mainly determined by the parameters of the beam and the atmosphere.
Abstract: Analytical formula is derived for the M2-factor of coherent and partially coherent dark hollow beams (DHB) in turbulent atmosphere based on the extended Huygens-Fresnel integral and the second-order moments of the Wigner distribution function. Our numerical results show that the M2- factor of a DHB in turbulent atmosphere increases on propagation, which is much different from its invariant properties in free-space, and is mainly determined by the parameters of the beam and the atmosphere. The relative M2-factor of a DHB increases slower than that of Gaussian and flat-topped beams on propagation, which means a DHB is less affected by the atmospheric turbulence than Gaussian and flat-topped beams. Furthermore, the relative M2-factor of a DHB with lower coherence, longer wavelength and larger dark size is less affected by the atmospheric turbulence. Our results will be useful in long-distance free-space optical communications.

131 citations

Journal ArticleDOI
TL;DR: In this article, the average intensity of flat-topped beams propagating in a turbulent atmosphere is derived in a tensor form, and the formulae derived can be easily reduced to those for flat-top beams in free space.
Abstract: The propagation of flat-topped beams with circular, elliptical and rectangular symmetries in a turbulent atmosphere is investigated. Analytical formulae for the average intensity of various flat-topped beams propagating in a turbulent atmosphere are derived in a tensor form. The formulae derived can easily be reduced to those for flat-topped beams propagating in free space (in the absence of turbulence). The propagation properties of flat-topped beams are studied in detail. We find that a flat-topped beam with circular or non-circular symmetry will evolve into a circular Gaussian beam in the far field under the influence of atmospheric turbulence, which is quite different to its properties in free space. Our method provides an effective and convenient way to analyse the propagation of various flat-topped beams in a turbulent atmosphere.

126 citations

Journal ArticleDOI
TL;DR: The experimental generation of a high-quality partially coherent dark hollow beam (DHB) is reported by coupling a partially coherent beam into a multimode fiber (MMF) with a suitable incidence angle by closely controlled coherence of the input beam.
Abstract: We report the experimental generation of a high-quality partially coherent dark hollow beam (DHB) by coupling a partially coherent beam into a multimode fiber (MMF) with a suitable incidence angle. The interference experiment of the generated partially coherent DHB passing through double slits is demonstrated. It is found that the coupling efficiency of the MMF, the quality, and the coherence of the generated partially coherent DHB are closely controlled by the coherence of the input beam.

87 citations

Journal ArticleDOI
TL;DR: In this article, the propagation properties of an off-axis Gaussian Schell model (GSM) beam in a turbulent atmosphere were investigated based on the extended Huygens-Fresnel integral formula.

87 citations

Journal ArticleDOI
TL;DR: In this paper, the on-axis scintillation index for a circular dark hollow beam (DHB) propagating in a weak turbulent atmosphere is formulated, and the scintillator properties of a DHB are investigated in detail.
Abstract: The on-axis scintillation index for a circular dark hollow beam (DHB) propagating in a weak turbulent atmosphere is formulated, and the scintillation properties of a DHB are investigated in detail. The scintillation index for a DHB reduces to the scintillation index for a Gaussian beam, an annular beam and a flat-topped beam under certain conditions. It is found that the scintillation index of a DHB is closely related to the beam parameters and can be lower than that of a Gaussian beam, an annular beam and a flat-topped beam in a weak turbulent atmosphere at smaller waist sizes and longer propagation lengths.

78 citations