Tailored spectral rotation of vortex pulses by non-uniform spiral phase gratings

Author(s):

Liebmann, Max; Treffer, Alexander; Bock, Martin; Jurke, Mathias; Wallrabe, Ulrike & Grunwald, Rüdiger

Abstract:

“Previously we studied the spectral Gouy rotation as a specific rotational phenomenon of conical polychromatic light fields shaped by spiral gratings. The rotation of spectral anomalies around singularities results from accumulated spectrally dependent Gouy phase shift. We proposed to apply radially chirped spiral structures to obtain an axial modulation of the rotational characteristics. Here we present related experimental results with non-uniform spiral gratings which were programmed into a 10-Megapixel, phase-only, liquid-crystal-on-silicon (LCoS) spatial light modulator (SLM). A propagation-dependent variation of the Gouy rotation was indicated. More complex non-uniform geometries are considered.”

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Publication: SPIE Proceedings, Complex Light and Optical Forces XV;
Issue/Year: Proc. SPIE 11701, Complex Light and Optical Forces XV, 117010V, 2021
DOI: 10.1117/12.2578503

Rotational Doppler effect detection by LG beams with a nonzero radial index

Author(s):

Qiu, Song; Ren, Yuan; Liu, Tong; Li, Zhimeng; Liu, Zhengliang; Wang, Chen; Ding, You & Sha, Qimeng

Abstract:

“The capability to detect the rotational speed of non-cooperative targets in a long distance is a difficult problem to be solved. In recent years, vortex light provides a feasible solution for the measurement of rotational speed for its spiral phase and the orbital angular momentum. Laguerre-Gaussian (LG) mode, as the typical vortex beam, has been widely employed in rotational Doppler effect (RDE) experiments. Here, we show that the nonzero radial index LG beam not only has a specific physical meaning but also can enhance the light intensity and the amplitude of RDE frequency signal relative to a zero radial index LG beam. To this end, we theoretically analyze the reason of intensity enhancement of a nonzero radial index beam and verify the conclusion in a variable control experiment. Our study provides a new aspect of LG beams that can be considered in rotational speed detection based on RDE. It may produce an improvement of the detection range of rotating targets in practical applications.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 7; Pages 10275; 2021
DOI: 10.1364/oe.421705

Long-range quasi-non-diffracting Gauss-Bessel beams in a few-cycle laser field

Author(s):

Stoyanov, Lyubomir; Zhang, Yinyu; Dreischuh, Alexander & Paulus, Gerhard G.

Abstract:

“Many applications ranging from nonlinear optics to material processing would benefit from pulsed ultrashort (quasi-)non-diffracting Gauss-Bessel beams (GBBs). Here we demonstrate a straightforward yet efficient method for generating such zeroth- and first-order GBBs using a single reflective spatial light modulator. Even in the sub-8-fs range there are no noticeable consequences for the measured pulse duration. The only effect is a weak “coloring” of the outer-lying satellite rings of the beams due to the spectrum spanning over more than 300 nm. The obtained beams have diffraction half-angles below 40 μrad and reach propagation distances in excess of 1.5 m.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 7; Pages 10997; 2021
DOI: 10.1364/oe.419486

Tailoring a complex perfect optical vortex array with multiple selective degrees of freedom

Author(s):

Wang, Hao; Fu, Shiyao & Gao, Chunqing

Abstract:

“Optical vortex arrays (OVAs) have successfully aroused substantial interest from researchers for their promising prospects ranging from classical to quantum physics. Previous reported OVAs still show a lack of controllable dimensions which may hamper their applications. Taking an isolated perfect optical vortex (POV) as an array element, whose diameter is independent of its topological charge (TC), this paper proposes combined phase-only holograms to produce sophisticated POV arrays. The contributed scheme enables dynamically controllable multi-ring, TC, eccentricity, size, and the number of optical vortices (OVs). Apart from traditional single ring POV element, we set up a βg library to obtain optimized double ring POV element. With multiple selective degrees of freedom to be chosen, a series of POV arrays are generated which not only elucidate versatility of the method but also unravel analytical relationships between the set parameters and intensity patterns. More exotic structures are formed like the “Bear POV” to manifest the potential of this approach in tailoring customized structure beams. The experimental results show robust firmness with the theoretical simulations. As yet, these arrays make their public debut so far as we know, and will find miscellaneous applications especially in multi-microparticle trapping, large-capacity optical communications, novel pumping lasers and so on.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 7; Pages 10811; 2021
DOI: 10.1364/oe.422301

Non-diffracting and self-accelerating Bessel beams with on-demand tailored intensity profiles along arbitrary trajectories

Author(s):

Yan, Wenxiang; Gao, Yuan; Yuan, Zheng; Wang, Zhuang; Ren, Zhi-Cheng; Wang, Xi-Lin; Ding, Jianping & Wang, Hui-Tian

Abstract:

“Owing to their robustness against diffraction, Bessel beams (BBs) offer special advantages in various applications. To enhance their applicability, we present a method to generate self-accelerating zeroth-order BBs along predefined trajectories with tunable z-direction intensity profiles. The character of tunable direction intensity profiles in non-diffracting self-accelerating BBs potentially can attract interest in the regimes of particle manipulation, microfabrication, and free-space optical interconnects.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Volume 46; Number 7; Pages 1494; 2021
DOI: 10.1364/ol.418928

2.5D Microscopy: Fast, High-Throughput Imaging via Volumetric Projection for Quantitative Subcellular Analysis

Author(s):

Ren, Jinhan & Han, Kyu Young

Abstract:

“Imaging-based single-cell analysis is essential to study the expression level and functions of biomolecules at subcellular resolution. However, its low throughput has prevented the measurement of numerous cellular features from multiples cells in a rapid and efficient manner. Here we report 2.5D microscopy that significantly improves the throughput of fluorescence imaging systems while maintaining high-resolution and single-molecule sensitivity. Instead of sequential z-scanning, volumetric information is projected onto a 2D image plane in a single shot by engineering the emitted fluorescence light. Our approach provides an improved imaging speed and uniform focal response within a specific imaging depth, which enabled us to perform quantitative single-molecule RNA measurements over a 2 × 2 mm² region within an imaging depth of ∼5 μm for mammalian cells in <10 min and immunofluorescence imaging at a >30 Hz volumetric frame rate with reduced photobleaching. Our microscope also offers the ability of multicolor imaging, depth control, and super-resolution imaging.”

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Publication: ACS Photonics
Issue/Year: ACS Photonics, Volume 8; Number 3; Pages 933-942; 2021
DOI: 10.1021/acsphotonics.1c00012

High-dimensional orbital angular momentum multiplexing nonlinear holography

Author(s):

Fang, Xinyuan; Yang, Haocheng; Yao, Wenzhe; Wang, Tianxin; Zhang, Yong; Gu, Min & Xiao, Min

Abstract:

“Nonlinear holography has been identified as a vital platform for optical multiplexing holographybecause of the appearance of new optical frequencies. However, due to nonlinear wave coupling innonlinear optical processes, the nonlinear harmonic field is coupled with the input field, laying a fundamentalbarrier to independent control of the interacting fields for holography. We propose and experimentallydemonstrate high-dimensional orbital angular momentum (OAM) multiplexing nonlinear holography toovercome this problem. By dividing the wavefront of the fundamental wave into different orthogonal OAMchannels, multiple OAM and polarization-dependent holographic images in both the fundamental wave andsecond-harmonic wave have been reconstructed independently in the spatial frequency domain through atype-II second harmonic generation process. Moreover, this method can be easily extended to cascaded χ2 nonlinear optical processes for multiplexing in more wavelength channels, leading to potential applicationsin multicasting in optical communications, multiwavelength display, multidimensional optical storage, anti-counterfeiting, and optical encryption.”

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Publication: Advanced Photonics
Issue/Year: Advanced Photonics, Volume 3; Number 01; 2021
DOI: 10.1117/1.ap.3.1.015001

Giant Helical Dichroism of Single Chiral Nanostructures with Photonic Orbital Angular Momentum

Author(s):

Ni, Jincheng; Liu, Shunli; Hu, Guangwei; Hu, Yanlei; Lao, Zhaoxin; Li, Jiawen; Zhang, Qing; Wu, Dong; Dong, Shaohua; Chu, Jiaru & Qiu, Cheng-Wei

Abstract:

“Optical activity, demonstrating the chiral light-matter interaction, has attracted tremendous attention in both fundamental theoretical research and advanced applications of high-efficiency enantioselective sensing and next-generation chiroptical spectroscopic techniques. However, conventional chiroptical responses are normally limited in large assemblies of chiral materials by circularly polarized light, exhibiting extremely weak chiroptical signals in a single chiral nanostructure. Here, we demonstrate that an alternative chiral freedom of light—orbital angular momentum—can be utilized for generating strong helical dichroism in single chiral nanostructures. The helical dichroism by monochromatic vortex beams can unambiguously distinguish the intrinsic chirality of nanostructures, in an excellent agreement with theoretical predictions. The single planar-chiral nanostructure can exhibit giant helical dichroism of ∼20% at the visible wavelength. The vortex-dependent helical dichroism, expanding to single nanostructures and two-dimensional space, has implications for high-efficiency chiroptical detection of planar-chiral nanostructures in chiral optics and nanophotonic systems.”

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Publication: ACS Nano
Issue/Year: ACS Nano, Volume 15; Number 2; Pages 2893-2900; 2021
DOI: 10.1021/acsnano.0c08941

Zeroth- and first-order long range non-diffracting GausstextendashBessel beams generated by annihilating multiple-charged optical vortices

Author(s):

Stoyanov, Lyubomir; Zhekova, Maya; Stefanov, Aleksander; Stefanov, Ivan; Paulus, Gerhard G. & Dreischuh, Alexander

Abstract:

“We demonstrate an alternative approach for generating zeroth- and first-order long range non-diffracting Gauss–Bessel beams (GBBs). Starting from a Gaussian beam, the key point is the creation of a bright ring-shaped beam with a large radius-to-width ratio, which is subsequently Fourier-transformed by a thin lens. The phase profile required for creating zeroth-order GBBs is flat and helical for first-order GBBs with unit topological charge (TC). Both the ring-shaped beam and the required phase profile can be realized by creating highly charged optical vortices by a spatial light modulator and annihilating them by using a second modulator of the same type. The generated long-range GBBs are proven to have negligible transverse evolution up to 2 m and can be regarded as non-diffracting. The influences of the charge state of the TCs, the propagation distance behind the focusing lens, and the GBB profiles on the relative intensities of the peak/rings are discussed. The method is much more efficient as compared to this using annular slits in the back focal plane of lenses. Moreover, at large propagation distances the quality of the generated GBBs significantly surpasses this of GBBs created by low angle axicons. The developed analytical model reproduces the experimental data. The presented method is flexible, easily realizable by using a spatial light modulator, does not require any special optical elements and, thus, is accessible in many laboratories.”

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Publication: Scientific Reports
Issue/Year: Scientific Reports, Volume 10; Number 1; 2020
DOI: 10.1038/s41598-020-78613-7

Gigantic vortical differential scattering as a monochromatic probe for multiscale chiral structures

Author(s):

Ni, Jincheng; Liu, Shunli; Wu, Dong; Lao, Zhaoxin; Wang, Zhongyu; Huang, Kun; Ji, Shengyun; Li, Jiawen; Huang, Zhixiang; Xiong, Qihua; Hu, Yanlei; Chu, Jiaru & Qiu, Cheng-Wei

Abstract:

“Spin angular momentum of light is vital to investigate enantiomers characterized by circular dichroism (CD), widely adopted in biology, chemistry, and material science. However, to discriminate chiral materials with multiscale features, CD spectroscopy normally requires wavelength-swept laser sources as well as wavelength-specific optical accessories. Here, we experimentally demonstrate an orbital-angular-momentum-assisted approach to yield chiroptical signals with monochromatic light. The gigantic vortical differential scattering (VDS) of ∼120% is achieved on intrinsically chiral microstructures fabricated by femtosecond laser. The VDS measurements can robustly generate chiroptical properties on microstructures with varying geometric features (e.g., diameters and helical pitches) and detect chiral molecules with high sensitivity. This VDS scheme lays a paradigm-shift pavement toward efficiently chiroptical discrimination of multiscale chiral structures with photonic orbital angular momentum. It simplifies and complements the conventional CD spectroscopy, opening possibilities for measuring weak optical chirality, especially on mesoscale chiral architectures and macromolecules.”

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Publication: Proceedings of the National Academy of Sciences
Issue/Year: Proceedings of the National Academy of Sciences, Volume 118; Number 2; Pages e2020055118; 2020
DOI: 10.1073/pnas.2020055118