Modal power decomposition of light propagating through multimode optical fiber

Большаков, М.В.; Кундикова, Н. Д.; Vlazneva, Marianna A.

doi:10.1016/j.optcom.2015.11.059

Cited by 3 publications

(1 citation statement)

References 12 publications

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“…Pu Zhou and Haibin LÜ and Liangjin Huang proposed an approach based on stochastic parallel gradient descent algorithm for a comprehensive optical fiber modal decomposition [9,10]. Maxim V. Bolshakov verified a numerical algorithm based on the cross-correlation operation of light intensity for modal power decomposition [11]. Thomas Kaiser presented a computer-generated holographic filter to characterize the laser beam, even if it had singularities [12,13].…”

Section: Introductionmentioning

confidence: 99%

Simulation of defocusing effect based on two-step ABCD algorithm while a modal decomposition

et al. 2020

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Depicting the multimode laser beam by modal decomposition can potentially assess light field variations in the fiber, during propagation. The practical engineering conditions in the lab however could not realize ideal levels, hence further research on factors influencing this method, such as defocus, is especially necessitated. The grid spacing in observation plane by Fast Fourier Transform is fixed and unchangeable within diffraction imaging, hence possibly yielding erroneous data during obtaining light field intensities. Our research resolves these issues via a Two-step ABCD algorithm, applied in the modal decomposition to characterize various guided modes at the output of multimode fibers. A direct benefit is that the image plane size can be altered, further refining laser facula clarity. Furthermore, the quantitative expressions that analyze defocus factors impacting modal decomposition are acquired. The conclusions thereby prove the modal decomposition algorithm can keep effectiveness in the range of −0.25% to 0.25% of relative defocus for low order eigenmodes, having no suitable limited band for high order eigenmodes, with reference value in engineering applications.

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Section: Introductionmentioning

confidence: 99%

Simulation of defocusing effect based on two-step ABCD algorithm while a modal decomposition

et al. 2020

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Modal decomposition of an incoherent combined laser beam based on the combination of residual networks and a stochastic parallel gradient descent algorithm

CHEN

2022

Appl. Opt.

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With the increase of the superimposed eigenmodes number, the traditional numerical modal decomposition (MD) technique will inevitably suffer from ambiguity and local minima problems and thus is typically unsuitable for conducting modal decomposition of an incoherent combined laser beam. In this paper, we propose a novel, to the best of our knowledge, MD algorithm, named ResNet-SPGD, which combines the advantages of residual networks (ResNet) and stochastic parallel gradient descent (SPGD) algorithm. Via setting the modal mode coefficients obtained from the CNN model as the initial value of the SPGD algorithm, such algorithm shows an attractive solution to mitigate the problem of modal ambiguity. The proposed algorithm is preliminarily applied to the modal decomposition of an incoherent combined laser beam, and the feasibility is demonstrated via numerical simulations. Complete MD is performed with high accuracy, and the only cost is the sacrifice of some real-time capacity.

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Joint effect of polarization and the propagation path of a light beam on its intrinsic structure

Abdulkareem¹,

Кундикова²

2016

Opt. Express

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The well-known effects of the spin-orbit interaction of light are manifestations of pair mutual influence of the three types of the angular momentum of light, namely, the spin angular momentum, the extrinsic orbital angular momentum and the intrinsic orbital angular momentum. Here we propose the convenient classification of the effects of the spin-orbit interaction of light and we observe one of the new effects in the frame of this classification, which is determined by the joint influence of two types of the angular momentum on the third type of the angular momentum, namely, the influence of the spin angular momentum and the extrinsic orbital angular momentum on the intrinsic orbital angular momentum. We experimentally studied the propagation of circularly polarized light through an optical fiber coiled into a helix. We have found that the spin angular momentum and the helix parameters affect the spatial structure of the radiation transmitted through the optical fiber. We found out that the structure of the light field rotates when changing the sign of circular polarization. The angle of rotation depends on the parameters of the helix. The results can be used to develop the general theory of spinning particles and can find application in metrology methods and nanooptics devices. Structured light beams carry three types of angular momentum [1][2][3][4]. The spin angular momentum is associated with polarization, the extrinsic orbital angular momentum is determined by the propagation path of the light beam, and the intrinsic orbital angular momentum is determined by the structure of the light field of the beam [3]. The effect of one of the angular momenta on another angular momentum leads to the spin-orbit interaction of light (a photon) [5,6]. There are six variants of such effects.The spin angular momentum affects the extrinsic orbital angular momentum, the effect can be observed as the longitudinal shift of the centroid of a linearly polarized light beam and the transverse shift of the centroid of a circularly polarized light beam at reflection and refraction and in focused light beams. These shifts are known as the Goos-Hanchen shift [7], the Imbert-Fedorov shift [8][9][10], the Hall effect for light [11], the optical Magnus effect [12] and the shift of the beam waist [13][14][15].The extrinsic orbital angular momentum affects the spin angular momentum, the effect manifests itself as the rotation of the linear polarization of light when changing * kundikovand@susu.ru the light propagation path [16][17][18][19]. The effect is known as the Rytov-Vladimirski-Berry-Chao-Wu-Tomita geometric polarization rotation. It can be observed in a single mode fiber, coiled into a helix [20], or in a multimode optical fiber [21].The intrinsic orbital angular momentum affects the extrinsic orbital angular momentum, the effect manifests itself as the shift of the centroid of a vortex light beam under reflection and refraction [3,[22][23][24].The extrinsic orbital angular momentum affects the intrinsic orbital angular momentum, t...

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Modal power decomposition of light propagating through multimode optical fiber

Cited by 3 publications

References 12 publications

Simulation of defocusing effect based on two-step ABCD algorithm while a modal decomposition

Simulation of defocusing effect based on two-step ABCD algorithm while a modal decomposition

Modal decomposition of an incoherent combined laser beam based on the combination of residual networks and a stochastic parallel gradient descent algorithm

Joint effect of polarization and the propagation path of a light beam on its intrinsic structure

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