Analysis of fractional vortex beams using a vortex grating spectrum analyzer

Zhang, Ning; Davis, Jeffrey A.; Moreno, Ignacio; Lin, Jiao; Moh, K. J.; Cottrell, Don M.; Yuan, Xiaocong

doi:10.1364/ao.49.002456

Cited by 46 publications

(17 citation statements)

References 22 publications

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“…The patterns depicted in Fig. 1(b) are similar to the results when using SPPs with fractional TCs [22]. The main lobe denotes the orientation of enhancement.…”

Section: Numerical Results and Discussionsupporting

confidence: 67%

Fractional spiral zone plates

et al. 2013

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In this paper, we generalize the concept of classical spiral zone plates (SZPs) to fractional spiral zone plates (FSZPs). By using an SZP with a fractional topological charge and controlling the starting orientation, we can break down the symmetry of the focusing process to give orientation-selective anisotropic vortex foci. Numerical results show that its binary structure gives additional high-order foci on the optical axis and the intensities in the foci can be controlled by properly choosing the fractional topological charge. Our study reveals the feasibility to control the intensity in the foci by means of FSZPs.

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“…The patterns depicted in Fig. 1(b) are similar to the results when using SPPs with fractional TCs [22]. The main lobe denotes the orientation of enhancement.…”

Section: Numerical Results and Discussionsupporting

confidence: 67%

Fractional spiral zone plates

et al. 2013

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“…Various methods have been proposed for measuring and recognizing OAM modes separated by a fractional interval. Some representative ways are based on specifically designed phase elements, which range from a conventional fork hologram 25 , 26 to an annular grating 27 , multifocal arrays 28 , and mode sorters utilizing optical coordinate transformation 29 , 30 . These methods can obtain quantitative values of fractional OAM by measuring either intensity or focal spot displacement, but there are drawbacks to be improved, such as a low resolution, precision, and a need for additional optical elements.…”

Section: Introductionmentioning

confidence: 99%

Deep-learning-based high-resolution recognition of fractional-spatial-mode-encoded data for free-space optical communications

2021

Sci Rep

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Structured light with spatial degrees of freedom (DoF) is considered a potential solution to address the unprecedented demand for data traffic, but there is a limit to effectively improving the communication capacity by its integer quantization. We propose a data transmission system using fractional mode encoding and deep-learning decoding. Spatial modes of Bessel-Gaussian beams separated by fractional intervals are employed to represent 8-bit symbols. Data encoded by switching phase holograms is efficiently decoded by a deep-learning classifier that only requires the intensity profile of transmitted modes. Our results show that the trained model can simultaneously recognize two independent DoF without any mode sorter and precisely detect small differences between fractional modes. Moreover, the proposed scheme successfully achieves image transmission despite its densely packed mode space. This research will present a new approach to realizing higher data rates for advanced optical communication systems.

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“…The combination of the vortex grating with a Dammann grating allows generating vortex diffraction orders with the same intensity 12 . Therefore, this Dammann vortex grating can be used as a vortex spectrum analyzer, where the different weights of vortex charges can be measured by the relative intensities at the center of the corresponding diffraction order 4 , 13 .…”

Section: Introductionmentioning

confidence: 99%

Vector Beam Polarization State Spectrum Analyzer

Moreno

Davis

Badham

et al. 2017

Sci Rep

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We present a proof of concept for a vector beam polarization state spectrum analyzer based on the combination of a polarization diffraction grating (PDG) and an encoded harmonic q-plate grating (QPG). As a result, a two-dimensional polarization diffraction grating is formed that generates six different q-plate channels with topological charges from −3 to +3 in the horizontal direction, and each is split in the vertical direction into the six polarization channels at the cardinal points of the corresponding higher-order Poincaré sphere. Consequently, 36 different channels are generated in parallel. This special polarization diffractive element is experimentally demonstrated using a single phase-only spatial light modulator in a reflective optical architecture. Finally, we show that this system can be used as a vector beam polarization state spectrum analyzer, where both the topological charge and the state of polarization of an input vector beam can be simultaneously determined in a single experiment. We expect that these results would be useful for applications in optical communications.

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Analysis of fractional vortex beams using a vortex grating spectrum analyzer

Cited by 46 publications

References 22 publications

Fractional spiral zone plates

Fractional spiral zone plates

Deep-learning-based high-resolution recognition of fractional-spatial-mode-encoded data for free-space optical communications

Vector Beam Polarization State Spectrum Analyzer

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