Real and virtual propagation dynamics of angular accelerating white light beams

Author(s):

Christian Vetter and Angela Dudley and Alexander Szameit and Andrew Forbes

Abstract:

“Accelerating waves have received significant attention of late, first in the optical domain and later in the form of electron matter waves, and have found numerous applications in non-linear optics, material processing, microscopy, particle manipulation and laser plasma interactions. Here we create angular accelerating light beams with a potentially unlimited acceleration rate. By employing wavelength independent digital holograms for the creation and propagation of white light beams, we are able to study the resulting propagation in real and virtual space. We find that dephasing occurs for real propagation and that this can be compensated for in a virtual propagation scheme when single plane dynamics are important. Our work offers new insights into the propagation dynamics of such beams and provides a versatile tool for further investigations into propagating structured light fields.”

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Publication: Optics Express
Issue/Year: Optics Express Vol. 25, Issue 17, pp. 20530-20540 (2017)
DOI: 10.1364/OE.25.020530

Non-diffractive Bessel-Gauss beams for the detection of rotating object free of obstructions

Author(s):

Shiyao Fu and Tonglu Wang and Zheyuan Zhang and Yanwang Zhai and Chunqing Gao

Abstract:

“Bessel-Gauss beams carrying orbital angular momentum are widely known for their non-diffractive or self-reconstructing performance, and have been applied in lots of domains. Here we demonstrate that, by illuminating a rotating object with high-order Bessel-Gauss beams, a frequency shift proportional to the rotating speed and the topological charge is observed. Moreover, the frequency shift is still present once an obstacle exists in the path, in spite of the decreasing of received signals. Our work indicates the feasibility of detecting rotating objects free of obstructions, and has potential as obstruction-immune rotation sensors in engine monitoring, aerological sounding, and so on.”

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Publication: Optics Express
Issue/Year: Optics Express , Vol. 25, Issue 17, pp. 20098- 20108 (2018)
DOI: 10.1364/OE.25.020098

Non-diffractive Bessel-Gauss beams for the detection of rotating object free of obstructions

Author(s):

Shiyao Fu and Tonglu Wang and Zheyuan Zhang and Yanwang Zhai and Chunqing Gao

Abstract:

“Bessel-Gauss beams carrying orbital angular momentum are widely known for their non-diffractive or self-reconstructing performance, and have been applied in lots of domains. Here we demonstrate that, by illuminating a rotating object with high-order Bessel- Gauss beams, a frequency shift proportional to the rotating speed and the topological charge is observed. Moreover, the frequency shift is still present once an obstacle exists in the path, in spite of the decreasing of received signals. Our work indicates the feasibility of detecting rotating objects free of obstructions, and has potential as obstruction-immune rotation sensors in engine monitoring, aerological sounding, and so on.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express Volume 25, Issue 17 pp. 20098-20108 (2017)
DOI: 10.1364/oe.25.020098

Resolving images by blurring: superresolution method with a scattering mask between the observed objects and the hologram recorder

Author(s):

Yuval Kashter and A. Vijayakumar and Joseph Rosen

Abstract:

“An important quest in optical imaging has been, and still is, extending the resolution of imaging systems beyond the diffraction limit. We propose a superresolution technique in which the image is first blurred by a scattering mask, and then recovered from the blurry data with improved resolution. We introduced a scattering mask into the space between the observed objects and the objective lens of a Fresnel incoherent correlation holography (FINCH) system to demonstrate the method. Optical waves, containing high spatial frequencies of the object, which are usually filtered out by the limited system aperture, were introduced into the system due to the scattering nature of the scattering mask. As a consequence, both the effective numerical aperture and the spatial bandwidth of the system were enlarged. The image resolution could therefore be improved far beyond the resolution limit dictated by the limited numerical aperture of the system. We demonstrated the technique using a modified FINCH system and the results were compared with other systems, all having the same aperture dimensions. We showed a resolution enhancement in comparison to conventional FINCH and regular imaging systems, with the same numerical apertures. The theoretical and experimental data presented here establishes the proposed method as an attractive platform for an advanced superresolution system that can resolve better than conventional imaging systems.”

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Publication: Optica
Issue/Year: Optica, Vol. 4, Issue 8, (2017)
DOI: 10.1364/OPTICA.4.000932

Axial sub-Fourier focusing of an optical beam

Author(s):

Thomas Zacharias and Barak Hadad and Alon Bahabad and Yaniv Eliezer

Abstract:

“We demonstrate experimentally the generation of an optical beam having an axial focusing that is narrower than the Fourier limit. The beam is constructed from a superposition of Bessel beams with different longitudinal wave vectors, realizing a super-oscillatory axial intensity distribution. Such beams can be useful for microscopy and for optical particle manipulation.”

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Publication: Optics Letters
Issue/Year: Optics Letters Vol. 42, Issue 16, pp. 3205-3208 (2017)
DOI: 10.1364/OL.42.003205

Tightly focused optical field with controllable photonic spin orientation

Author(s):

Jian Chen and Chenhao Wan and Ling Jiang Kong and Qiwen Zhan

Abstract:

“The spin angular momentum of photons offers a robust, scalable and highbandwidth toolbox for many promising applications based upon spin-controlled manipulations of light. In this work, we develop a method to achieve controllable photonic spin orientation within a diffraction limited optical focal spot produced by a high numerical aperture objective lens. The required pupil field is found analytically through reversing the radiation patterns from two electric dipoles located at the focal point of the lens with orthogonal oscillation directions and quadrature phase. The calculated pupil fields are experimentally generated with a vectorial optical field generator. The produced photonic spin orientations are quantitatively evaluated by their spin densities according to the tightly focused electric fields calculated by Richard-Wolf vectorial diffraction theory to demonstrate the validity and capability of the proposed technique.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 25, Number 16 pp. 19517-19528 (2017)
DOI: 10.1364/OE.25.019517

Experimental study on the propagation characteristics of ring Airy Gaussian vortex beams

Author(s):

Musheng Chen and Sujuan Huang and Wei Shao and Xianpeng Liu

Abstract:

“The auto-focusing and auto-healing profiles of linearly polarized ring Airy Gaussian vortex (RAiGV) beams in linear media are investigated experimentally
based on spatial light modulators and computer-generated holograms. It is found that the parameters of incident beams greatly affect the auto-focusing profiles of RAiGV. The focal length increases as the radius of the primary ring, scaling factor and waist radius increases, and the focal length decreases slightly as topological charges increase. The peak intensity at focal point increases with the increasing topological charges and waist radius, or with the decreasing scaling factor and the radius of the primary ring. The phase singularity of the RAiGV beams remains unchanged during propagation. The RAiGV beams also exhibit remarkable resilience against perturbations and tend to reconstruct its intensity sharp. Meanwhile, the abruptly auto-focusing property can be controlled by blocking few inner or outer rings of the RAiGV beams. These studies provide useful insight in the study of Airy vortex beam and its further applications”

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Publication: Applied Physics
Issue/Year: Applied Physics B 123:215 (2017)
DOI: 10.1007/s00340-017-6794-8

Free-space optical communication link using perfect vortex beams carrying orbital angular momentum ({OAM})

Author(s):

Fuquan Zhu and Sujuan Huang and Wei Shao and Jie Zhang and Musheng Chen and Weibing Zhang and Junzhang Zeng

Abstract:

“We experimentally demonstrate a free-space optical communication link using perfect vortex beams. Perfect vortex beams with different topological charges are generated using a phase-modulation-type spatial light modulator (SLM) loaded with novel phase holograms based on the Bessel function. With the help of a microscope objective and simple lens, perfect vortex beams are transmitted effectively for a certain distance. After completing the demodulation of perfect vortex beams carrying OFDM 16-QAM signals and a series of offline processing on the Gaussian bright spot demodulated from the perfect vortex beams, we also achieve a communication link. The constellations and mean bit error rates (BER) of subcarriers are shown.”

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Publication: Optics Communications
Issue/Year: Optics Communications Volume 396, Pages 50-57
DOI: 10.1016/j.optcom.2017.03.023