Generation of controllable spectrum in multiple positions from speckle patterns


Li, Haoran; Wu, Xiaoyan; Liu, Guodong; Vinu, R. V.; Wang, Xiaoyan; Chen, Ziyang & Pu, Jixiong


“Feedback-based wavefront shaping has been proposed to modulate the speckle field generated by coherent light transmitting through scattering media. Different from a monochromatic light, a colorful speckle pattern is generated when polychromatic light transmits through scattering media. Although single-position spectrum modulation has been realized, multiple-position spectrum modulation is a much more complicated problem. Based on non-dominated sorting genetic algorithm II (NSGA2), we design a step-by-step strategy to solve this problem. The results show that modulated spectra in two spatial positions with controllable spectral shape, range and magnitude can be achieved. This research is expected to be applied in the field of adaptive spectral control ranging from advanced spectral filtering to optical fiber dispersion and multi-spectral imaging.”

Link to Publications Page

Publication: Optics & Laser Technology
Issue/Year: Optics & Laser Technology, Volume 149; Pages 107820; 2022
DOI: 10.1016/j.optlastec.2021.107820

Speckle reduction in holographic display with partially spatial coherent illumination


Zhao, Zijie; Duan, Junyi & Liu, Juan


“A method of holographic reconstruction under partially spatial coherent illumination with different degree of coherence is proposed to suppress speckle noise based on theoretical analysis. The core factor of speckle reduction based on partially spatial coherent light is convolution operation in CGH reconstruction process. Numerical simulations and optical experiments are both performed to verify the proposed theory. The results reconstructed by proposed and traditional method are compared, and the speckle contrasts can be reduced to 0.05 and 0.08 at most in Fresnel and Fraunhofer zone respectively. The image quality is obviously improved. This method can provide further applications for three-dimensional holographic display, beam shaping and coherence degree modulation techniques.”

Link to Publications Page

Publication: Optics Communications
Issue/Year: Optics Communications, Volume 507; Pages 127604; 2022
DOI: 10.1016/j.optcom.2021.127604

Singularities splitting phenomenon for the superposition of hybrid orders structured lights and the corresponding interference discrimination method


Mao, Baiwei; Liu, Yange; Chang, Wenzhe; Chen, Liang; Feng, Mao; Guo, Huiyi; He, Jiangyong & Wang, Zhi


“It is the basic characteristic of pure vortex light

that there is a phase singularity at the origin. Such a sin-

gularity may be multiple degenerate, which determines the

order of vortex light. Singularities splitting phenomenon

means that singularities no longer concentrate at the origin

but distribute around the space, usually occurring in

impure vortex light. In this paper, we demonstrate the

singularities splitting phenomenon and propose an anal-

ysis method, based on which one may rapidly estimate the

modal components of impure vortex light. As two common

singularity discrimination methods, the spiral and fork

wire interference patterns are compared in distinguishing

splitting singularities. The most widely used spiral inter-

ference pattern is revealed to be the worst form because of

the low resolution. Instead, the fork wire interference

pattern is with higher and easily adjusted resolution. 1‰

impurity is still able to be distinguished through fork wire

interference patterns in the experiment.”

Link to Publications Page

Publication: Nanophotonics
Issue/Year: Nanophotonics, Volume 0; Number 0; 2022
DOI: 10.1515/nanoph-2021-0814

Large depth-of-field fluorescence microscopy based on deep learning supported by Fresnel incoherent correlation holography


Wu, Peng; Zhang, Dejie; Yuan, Jing; Zeng, Shaoqun; Gong, Hui; Luo, Qingming & Yang, Xiaoquan


“Fluorescence microscopy plays an irreplaceable role in biomedicine. However,

limited depth of field (DoF) of fluorescence microscopy is always an obstacle of image quality,

especially when the sample is with an uneven surface or distributed in different depths. In

this manuscript, we combine deep learning with Fresnel incoherent correlation holography to

describe a method to obtain significant large DoF fluorescence microscopy. Firstly, the hologram

is restored by the Auto-ASP method from out-of-focus to in-focus in double-spherical wave

Fresnel incoherent correlation holography. Then, we use a generative adversarial network to

eliminate the artifacts introduced by Auto-ASP and output the high-quality image as a result.

We use fluorescent beads, USAF target and mouse brain as samples to demonstrate the large

DoF of more than 400µm, which is 13 times better than that of traditional wide-field microscopy.

Moreover, our method is with a simple structure, which can be easily combined with many

existing fluorescence microscopic imaging technology”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Volume 30; Number 4; Pages 5177; 2022
DOI: 10.1364/oe.451409

Scalability of all-optical neural networks based on spatial light modulators


Ying Zuo, Zhao Yujun, You-Chiuan Chen, Shengwang Du & Liu, Junwei


“Optical implementation of artificial neural networks has been attracting great attention due to its potential in parallel computation at speed of light. Although all-optical deep neural networks (AODNNs) with a few neurons have been experimentally demonstrated with acceptable errors re- cently, the feasibility of large scale AODNNs remains unknown because error might accumulate inevitably with increasing number of neurons and connections. Here, we demonstrate a scalable AODNN with programmable linear operations and tunable nonlinear activation functions. We ver- ify its scalability by measuring and analyzing errors propagating from a single neuron to the entire network. The feasibility of AODNNs is further confirmed by recognizing handwritten digits and fashions respectively.”

Link to Publications Page

Publication: Physical Review Applied
Issue/Year: Physical Review Applied, 2021

Precise position and angular control of optical trapping and manipulation via a single vortex-pair beam


Jisen Wen, Binjie Gao, Guiyuan Zhu, DadongLiu, Li-GangWang


“Optical trapping and manipulation using structured laser beams now attract increasing attention in many areas including biology, atomic science, and nanofabrication. Here we propose and demonstrate experimentally the use of a single vortex-pair beam in two-dimensional optical trapping and manipulation. Using the focal properties of such vortex-pair beams, we successfully manipulate two spherical microparticles simultaneously, and obtain the precise position-control on the microparticles by adjusting the off-axis parameter of the vortex-pair beam. Furthermore, we also realize the high-precision angular-controllable rotation of cylindrical microrods by rotating the initial phase structure of such vortex-pair beams, which is like an optical wrench due to two focused bright spots at the focal plane of objective lens. Our experimental result provides an alternative manipulation of microparticles and may have potential applications in biological area, and optically driven micromachines or motors.”

Link to Publications Page

Publication: Optics and Lasers in Engineering
Issue/Year: Optics and Lasers in Engineering, Volume 148, 106773 (2022)
DOI: 10.1016/j.optlaseng.2021.106773

Discretized continuous quantum-mechanical observables that are neither continuous nor discrete


Thais L. Silva, Łukasz Rudnicki, Daniel S. Tasca, and Stephen P. Walborn


“Most of the fundamental characteristics of quantum mechanics, such as nonlocality and contextuality, are manifest in discrete, finite-dimensional systems. However, many quantum information tasks that exploit these properties cannot be directly adapted to continuous variable systems. To access these quantum features, continuous quantum variables can be made discrete by binning together their different values, resulting in observables with a finite number, d, of outcomes. While direct measurement indeed confirms their manifestly discrete character, here we employ a salient feature of quantum physics known as mutual unbiasedness to show that such coarse-grained observables are in a sense neither continuous nor discrete. Depending on d, the observables can reproduce either the discrete or the continuous behavior, or neither. To illustrate these results, we present an example for the construction of such measurements and employ it in an optical experiment confirming the existence of four mutually unbiased measurements with d=3 outcomes in a continuous variable system, surpassing the number of mutually unbiased continuous variable observables.”

Link to Publications Page

Publication: Physical Review Research
Issue/Year: Physical Review Research, Volume 4; Number 1; Pages 013060; 2022
DOI: 10.1103/physrevresearch.4.013060

Polygon-based computer-generated holography: a review of fundamentals and recent progress [Invited]


Zhang, Yaping; Fan, Houxin; Wang, Fan; Gu, Xianfeng; Qian, Xiaofan & Poon, Ting-Chung


“In this review paper, we first provide comprehensive tutorials on two classical methods of polygon-based computer-

generated holography: the traditional method (also called the fast-Fourier-transform-based method) and the

analytical method. Indeed, other modern polygon-based methods build on the idea of the two methods. We will

then present some selective methods with recent developments and progress and compare their computational

reconstructions in terms of calculation speed and image quality, among other things. Finally, we discuss and pro-

pose a fast analytical method called the fast 3D affine transformation method, and based on the method, we present

a numerical reconstruction of a computer-generated hologram (CGH) of a 3D surface consisting of 49,272 pro-

cessed polygons of the face of a real person without the use of graphic processing units; to the best of our knowledge,

this represents a state-of-the-art numerical result in polygon-based computed-generated holography. Finally, we

also show optical reconstructions of such a CGH and another CGH of the Stanford bunny of 59,996 polygons with

31,724 processed polygons after back-face culling. We hope that this paper will bring out some of the essence of

polygon-based computer-generated holography and provide some insights for future research.”

Link to Publications Page

Publication: Applied Optics
Issue/Year: Applied Optics, Volume 61; Number 5; Pages B363; 2022
DOI: 10.1364/ao.444973

High-Flexibility Control of Structured Light with Combined Adaptive Optical Systems


Grunwald, Rüdiger; Jurke, Mathias; Bock, Martin; Liebmann, Max; Bruno, Binal Poyyathuruthy; Gowda, Hitesh & Wallrabe, Ulrike


“Combining the specific advantages of high-resolution liquid-crystal-on-silicon spatial light modulators (LCoS-SLMs) and reflective or refractive micro-electro-mechanical systems (MEMS) presents new prospects for the generation of structured light fields. In particular, adaptive self-apodization schemes can significantly reduce diffraction by low-loss spatial filtering. The concept enables one to realize low-dispersion shaping of nondiffracting femtosecond wavepackets and to temporally switch, modulate or deflect spatially structured beams. Adaptive diffraction management by structured illumination is demonstrated for piezo-based and thermally actuated axicons, spiral phase plates (SPPs) and Fresnel bi-mirrors. Improved non-collinear autocorrelation with angular-tunable Fresnel-bi-mirrors via self-apodized illumination and phase contrast of an SLM is proposed. An extension of the recently introduced nondiffractive Talbot effect to a tunable configuration by combining an SLM and a fluid lens is reported. Experimental results for hexagonal as well as orthogonal array beams are presented.”

Link to Publications Page

Publication: Photonics
Issue/Year: Photonics, Volume 9; Number 1; Pages 42; 2022
DOI: 10.3390/photonics9010042

Electro-Optic Modulation of Higher-Order Poincar’e Beam Based on Nonlinear Optical Crystal


Han, Lu; Li, Zhan; Chen, Chao; Sun, Xin; Zhang, Junyong & Liu, Dean


“Vector beams (VBs) have spatially inhomogeneous polarization states distribution and have been widely used in many fields. In this paper, we proposed a method to modulate polarization states of higher-order Poincaré (HOP) beams and designed a system based on Mach-Zehnder interferometers, in which polarization state (include azimuth and ellipticity) of generated HOP beams were modulated by linear electro-optic (EO) effect of nonlinear optical crystals. Using this method, the polarization state of generated HOP beams could be controlled by voltage signal applied on EO crystals, which makes the process of the polarization state change with no optical element moving and mechanical vibrations. Besides, due to the flexibility of the voltage signal, the polarization state could be switched directly and immediately.”

Link to Publications Page

Publication: Photonics
Issue/Year: Photonics, Volume 9; Number 1; Pages 41; 2022
DOI: 10.3390/photonics9010041
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