Generation of vector elliptical perfect optical vortices with mixed modes in free space

Author(s):

Kang, Xiangyu; Shan, Xinzhi; Chen, Keyu; Sun, Xiaojie; Wang, Guanxue; Gao, Xiumin; Liu, Yi & Zhuang, Songlin

Abstract:

“Vector vortex beams are widely used because of their anisotropic vortex polarization state and spiral phase. Constructing mixed mode vector vortex beams in free space still requires complex designs and calculations. We propose a method for generating mixed mode vector Elliptical perfect optical vortex (EPOV) arrays in free space by mode extraction and optical pen. It is demonstrated that the long axis and short axis of EPOVs are not limited by the topological charge (TC). Flexible modulation of parameters in the array is achieved, including number, position, ellipticity, ring size, TC, and polarization mode. This approach is simple and effective, it will provide a powerful optical tool for optical tweezers, particle manipulation, and optical communication.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 31; Number 9; Pages 15179; 2023
DOI: 10.1364/oe.489196

Azimuthal backflow in light carrying orbital angular momentum

Author(s):

Ghosh, Bohnishikha; Daniel, Anat; Gorzkowski, Bernard & Lapkiewicz, Radek

Abstract:

“M.V. Berry’s work [J. Phys. A: Math. Theor. 43, 415302 (2010)] highlighted the correspondence
between backflow in quantum mechanics and superoscillations in waves. Superoscillations refer to
situations where the local oscillation of a superposition is faster than its fastest Fourier component.
This concept has been used to demonstrate backflow in transverse linear momentum for optical
waves. In this work, we examine the interference of classical light carrying only negative orbital
angular momentum and observe in the dark fringes of such an interference, positive local orbital
angular momentum. This finding may have implications for the studies of light-matter interaction
and represents a step towards observing quantum backflow in two dimensions.”

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Publication: arXiv
Issue/Year: arXiv, 2023
arXiv: 10.48550/arXiv.2304.13124

Multi-Plane Light Conversion: A Practical Tutorial

Author(s):

Zhang, Yuanhang & Fontaine, Nicolas K.

Abstract:

“Multi-plane light conversion (MPLC) has recently been developed as a versatile tool for manipulating spatial distributions of the optical field through repeated phase modulations. An MPLC Device consists of a series of phase masks separated by free-space propagation. It can convert one orthogonal set of beams into another orthogonal set through unitary transformation, which is useful for a number of applications. In telecommunication, for example, mode-division multiplexing (MDM) is a promising technology that will enable continued scaling of capacity by employing spatial modes of a single fiber. MPLC has shown great potential in MDM devices with ultra-wide bandwidth, low insertion loss (IL), low mode-dependent loss (MDL), and low crosstalk. The fundamentals of design, simulation, fabrication, and characterization of practical MPLC mode (de)multiplexers will be discussed in this tutorial.”

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Publication: arXiv
Issue/Year: arXiv, 2023
DOI: 10.48550/arXiv.2304.11323

Encrypting orbital angular momentum holography with ghost imaging

Author(s):

Ma, Junyao; Li, Zhe; Zhao, Shengmei & Wang, Le

Abstract:

“In this paper, we propose a multiple images simultaneous encryption scheme by encrypting the orbital angular momentum (OAM) holography with ghost imaging. By controlling the topological charge of the incident OAM light beam on the OAM-multiplexing hologram, different images can be selectively obtained for ghost imaging (GI). Followed by the random speckles illumination, the bucket detector values in GI are obtained and then considered as the ciphertext transmitted to the receiver. The authorized user can distill the correct relationship between the bucket detections and the illuminating speckle patterns with the key and the additional topological charges, so that each holographic image can be successfully recovered, while the eavesdropper can not obtain any information about the holographic image without the key. The eavesdropper even can not get clear holographic image when all the key is eavesdropped but without topological charges. The experimental results show that the proposed encryption scheme has a higher capacity for multiple images because there is no theoretical topological charge limit for the selectivity of OAM holography, and the results also show that the proposed encryption scheme is more secure and has a stronger robustness. Our method may provide a promising avenue for multi-image encryption and has the potential for more applications.”

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Publication: Opt. Express
Issue/Year: Opt. Express, Volume 31; Number 7; Pages 11717–11728; 2023
DOI: 10.1364/OE.483923

Flow Cytometry with Anti-Diffraction Light Sheet (ADLS) by Spatial Light Modulation

Author(s):

Gong, Yanyan; Zeng, Ming; Zhu, Yueqiang; Li, Shangyu; Zhao, Wei; Zhang, Ce; Zhao, Tianyun; Wang, Kaige; Yang, Jiangcun & Bai, Jintao

Abstract:

“Flow cytometry is a widespread and powerful technique whose resolution is determined by its capacity to accurately distinguish fluorescently positive populations from negative ones. However, most informative results are discarded while performing the measurements of conventional flow cytometry, e.g., the cell size, shape, morphology, and distribution or location of labeled exosomes within the unpurified biological samples. Herein, we propose a novel approach using an anti-diffraction light sheet with anisotroic feature to excite fluorescent tags. Constituted by an anti-diffraction Bessel–Gaussian beam array, the light sheet is 12 μm wide, 12 μm high, and has a thickness of  0.8 μm . The intensity profile of the excited fluorescent signal can, therefore, reflect the size and allow samples in the range from O (100 nm ) to 10 μm (e.g., blood cells) to be transported via hydrodynamic focusing in a microfluidic chip. The sampling rate is 500 kHz, which provides a capability of high throughput without sacrificing the spatial resolution. Consequently, the proposed anti-diffraction light sheet flow cytometry (ADLSFC) can obtain more informative results than the conventional methodologies, and is able to provide multiple characteristics (e.g., the size and distribution of fluorescent signal) helping to distinguish the target samples from the complex backgrounds.”

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Publication: Micromachines
Issue/Year: Micromachines, Volume 14; Number 3; Pages 679; 2023
DOI: 10.3390/mi14030679

Generation of high-dimensional caustic beams via phase holograms using angular spectral representation

Author(s):

Sun, Zhuo; Hu, Juntao; Wang, Yishu; Ye, Wenni; Qian, Yixian & Li, Xinzhong

Abstract:

“Using angular spectral representation, we demonstrate a generalized approach for generating high-dimensional elliptic umbilic and hyperbolic umbilic caustics by phase holograms. The wavefronts of such umbilic beams are investigated via the diffraction catastrophe theory determined by the potential function, which depends on the state and control parameters. We find that the hyperbolic umbilic beams degenerate into classical Airy beams when the two control parameters are simultaneously equal to zero, and elliptic umbilic beams possess an intriguing autofocusing property. Numerical results demonstrate that such beams exhibit clear umbilics in 3D caustic, which link the two separated parts. The dynamical evolutions verify that they both possess prominent self-healing properties. Moreover, we demonstrate that hyperbolic umbilic beams follow along a curve trajectory during propagation. As the numerical calculation of diffraction integral is relatively complex, we have developed an effective approach for successfully generating such beams by using phase hologram represented by angular spectrum. Our experimental results are in good agreement with the simulations. Such beams with intriguing properties are likely to be applied in emerging fields such as particle manipulation and optical micromachining.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 31; Number 5; Pages 7480; 2023
DOI: 10.1364/oe.483169

Measurement of the fractional topological charge of an optical vortex beam through interference fringe dislocation

Author(s):

Shikder, Allarakha & Nishchal, Naveen K.

Abstract:

“An optical vortex beam carrying fractional topological charge (TC) has become an immerging field of interest due to its unique intensity distribution and fractional phase front in a transverse plane. Potential applications include micro-particle manipulation, optical communication, quantum information processing, optical encryption, and optical imaging. In these applications, it is necessary to know the correct information of the orbital angular momentum, which is related to the fractional TC of the beam. Therefore, the accurate measurement of fractional TC is an important issue. In this study, we demonstrate a simple technique to measure the fractional TC of an optical vortex with a resolution of 0.05 using a spiral interferometer and fork-shaped interference patterns. We further show that the proposed technique provides satisfactory results in cases of low to moderate atmospheric turbulences, which has relevance in free-space optical communications.”

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Publication: Applied Optics
Issue/Year: Applied Optics, Volume 62; Number 10; Pages D58; 2023
DOI: 10.1364/ao.476455

Simultaneously sorting vector vortex beams of 120 modes

Author(s):

Jia, Qi; Zhang, Yanxia; Shi, Bojian; Li, Hang; Li, Xiaoxin; Feng, Rui; Sun, Fangkui; Cao, Yongyin; Wang, Jian; Qiu, Cheng-Wei & Ding, Weiqiang

Abstract:

“Polarization (P), angular index (l), and radius index (p) are three independent degrees of freedom (DoFs) of vector vortex beams, which have been widely used in optical communications, quantum optics, information processing, etc. Although the sorting of one DoF can be achieved efficiently, it is still a great challenge to sort all these DoFs simultaneously in a compact and efficient way. Here, we propose a beam sorter to deal with all these three DoFs simultaneously by using a diffractive deep neural network (D^2NN) and experimentally demonstrated the robust sorting of 120 Laguerre-Gaussian (LG) modes using a compact D^2NN formed by one spatial light modulator and one mirror only. The proposed beam sorter demonstrates the great potential of D^2NN in optical field manipulation and will benefit the diverse applications of vector vortex beams.”

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Publication: arXiv
Issue/Year: arXiv, 2022
DOI: 10.48550/ARXIV.2212.08825

Modulation of Non-diffracting Hermite Gaussian Beams and Nonlinear Optical Microscopy for Nanoscale Sulfur Imaging

Author(s):

Navarro, Gilberto

Abstract:

“Hermite Gaussian beams are the solutions of the scalar paraxial wave equation in Cartesian coordinates. A method was developed to modulate the intensity profile of non-diffracting Hermite Gaussian (HG) beams. The original HG beams intensity profile consists of high intense corner lobes and low intense central lobes which is not ideal for structured illumination in light-field microscopy. The modulated HG beams were generated by multiplying the original HGâ??s beam envelope by a super-Gaussian envelope to modify the intensity profile to attain equal intensity lobes. The propagation of the original HG beam and modulated HG beam were compared to determine that the non-diffracting properties of the modulated HG beam were held.

Two-photon absorption (TPA) is a nonlinear optical process in which the absorption coefficient depends on the optical intensity. In the process of two-photon absorption, an atom makes a transition from its ground state to an excited state by the simultaneous (  1 fs) absorption of two photons. In the second project, two-photon microscopy was used to detect the root uptake and determine the biodistribution of nanoscale sulfur. Characterization of pristine, stearic acid coated, and bulk sulfur was done to determine their fluorescent signal properties. Tomatoes that were grown in nano-sulfur treated soils to enhance crop nutrition and suppress disease, were imagined under the two-photon microscope to detect the root uptake of the nanoscale sulfur.”

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Publication: University of Texas at El Paso, Thesis
Issue/Year: , 2022
URL: https://scholarworks.utep.edu/open_etd/3706

Simulated LCSLM with Inducible Diffractive Theory to Display Super-Gaussian Arrays Applying the Transport-of-Intensity Equation

Author(s):

Arriaga-Hernandez, Jesus; Cuevas-Otahola, Bolivia; Oliveros-Oliveros, Jacobo; Morin-Castillo, Maria; Martinez-Laguna, Ygnacio & Cedillo-Ramirez, Lilia

Abstract:

“We simulate a liquid crystal spatial light modulator (LCSLM), previously validated by Fraunhofer diffraction to observe super-Gaussian periodic profiles and analyze the wavefront of optical surfaces applying the transport-of-intensity equation (TIE). The LCSLM represents an alternative to the Ronchi Rulings, allowing to avoid all the related issues regarding diffractive and refractive properties, and noise. To this aim, we developed and numerically simulated a LCSLM resembling a fractal from a generating base. Such a base is constituted by an active square (values equal to one) and surrounded by eight switched-off pixels (zero-valued). We replicate the base in order to form 1 ×N-pixels and the successive rows to build the 1024×1024 LCSLM of active pixels. We visually test the LCSLM with calibration images as a diffractive object that is mathematically inducible, using mathematical induction over the N×N-shape (1×1, 2×2, 3×3, …, n×n pixels for the generalization). Finally, we experimentally generate periodic super-Gaussian profiles to be visualized in the LCSLM (transmission SLM, 1024×768-pixels LC 2012 Translucent SLM), modifying the TIE as an optical test in order to analyze the optical elements by comparing the results with ZYGO/APEX.”

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Publication: Photonics
Issue/Year: Photonics, Volume 10; Number 1; Pages 39; 2022
DOI: 10.3390/photonics10010039
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