Generation of Tunable Fractional Vector Curvilinear Beams With Controllable Phase Distribution

Author(s):

Fengyan Gu, Zhongzheng Gu, Chenliang Chang, Caojin Yuan, Shaotong Feng, Fangjian Xing and Shouping Nie

Abstract:

“An approach to generate the tunable fractional vector curvilinear beams (VCBs) was proposed. The scheme is based on the vector optical field generator (VOFG) system, where the two orthogonal polarized scalar curvilinear beams (SCBs) are generated to be the base vector components, and coaxially superposed by a Ronchi grating. We design a new phase distribution with several loops of 0 to π in order to generate more dark gaps. The phase distribution becomes nonuniform by varying the phase variation rate and the positions of the dark gaps are changed. Using the different parameters of the curves, the fractional VCBs with different shapes are achieved. The two orthogonal polarized SCBs with the opposite topological charges are modulated to perform the beam conversion by a phase-only computer-generated hologram (CGH). Our experimental results comply with the theory and the radial opening of the dark gaps may have some applications for guiding and transporting particles.”

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Publication: IEEE Photonics Journal
Issue/Year: Volume: 11 Issue: 6 (2019)
DOI: 10.1109/JPHOT.2019.2942041

Wirtinger holography for near-eye displays

Author(s):

Chakravarthula, Praneeth; Peng, Yifan; Kollin, Joel; Fuchs, Henry & Heide, Felix

Abstract:

“Near-eye displays using holographic projection are emerging as an exciting display approach for virtual and augmented reality at high-resolution without complex optical setups — shifting optical complexity to computation. While precise phase modulation hardware is becoming available, phase retrieval algorithms are still in their infancy, and holographic display approaches resort to heuristic encoding methods or iterative methods relying on various relaxations.
In this work, we depart from such existing approximations and solve the phase retrieval problem for a hologram of a scene at a single depth at a given time by revisiting complex Wirtinger derivatives, also extending our framework to render 3D volumetric scenes. Using Wirtinger derivatives allows us to pose the phase retrieval problem as a quadratic problem which can be minimized with first-order optimization methods. The proposed Wirtinger Holography is flexible and facilitates the use of different loss functions, including learned perceptual losses parametrized by deep neural networks, as well as stochastic optimization methods. We validate this framework by demonstrating holographic reconstructions with an order of magnitude lower error, both in simulation and on an experimental hardware prototype.”

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Publication: ACM Transactions on Graphics (TOG)
Issue/Year: ACM Transactions on Graphics (TOG), Volume 38; Number 6; Pages 213; 2019
DOI: 10.1145/3355089.3356539

Polarization nano-tomography of tightly focused light landscapes by self-assembled monolayers

Author(s):

Eileen Otte, Kemal Tekce, Sebastian Lamping, Bart Jan Ravoo and Cornelia Denz
Abstract:

“Recently, four-dimensional (4D) functional nano-materials have attracted considerable attention due to their impact in cutting-edge fields such as nano-(opto)electronics, -biotechnology or -biomedicine. Prominent optical functionalizations, representing the fourth dimension, require precisely tailored light fields for its optimal implementation. These fields need to be like-wise 4D, i.e., nano-structured in three-dimensional (3D) space while polarization embeds additional longitudinal components. Though a couple of approaches to realize 4D fields have been suggested, their breakthrough is impeded by a lack of appropriate analysis techniques. Combining molecular self-assembly, i.e., nano-chemistry, and nano-optics, we propose a polarization nano-tomography of respective fields using the functional material itself as a sensor. Our method allows a single-shot identification of non-paraxial light fields at nano-scale resolution without any data post-processing. We prove its functionality numerically and experimentally, elucidating its amplitude, phase and 3D polarization sensitivity. We analyze non-paraxial field properties, demonstrating our method’s capability and potential for next generation 4D materials.”

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Publication: Nature Communications
Issue/Year: Nature Communications volume 10, Article number: 4308 (2019)
DOI: 10.1038/s41467-019-12127-3

Encoding of arbitrary micrometric complex illumination patterns with reduced speckle

Author(s):

Miguel Carbonell-Leal, Gladys Mínguez-Vega, Jesús Lancis, and Omel Mendoza-Yero

Abstract:

“In nonlinear microscopy, phase-only spatial light modulators (SLMs) allow achieving simultaneous two-photon excitation and fluorescence emission from specific region-of-interests (ROIs). However, as iterative Fourier transform algorithms (IFTAs) can only approximate the illumination of selected ROIs, both image formation and/or signal acquisition can be largely affected by the spatial irregularities of the illumination patterns and the speckle noise. To overcome these limitations, we propose an alternative complex illumination method (CIM) able to generate simultaneous excitation of large-area ROIs with full control over the amplitude and phase of light and reduced speckle. As a proof-of-concept we experimentally demonstrate single-photon and second harmonic generation (SHG) with structured illumination over large-area ROIs.”

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Publication: Optics Express
Issue/Year: Vol. 27, Issue 14, pp. 19788-19801 (2019)
DOI: 10.1364/OE.27.019788

Liquid Crystal Spatial Light Modulator with Optimized Phase Modulation Ranges to Display Multiorder Diffractive Elements

Author(s):

Elisabet Pérez-Cabré; María S. Millán
Abstract:

“A liquid crystal on silicon spatial light modulator (LCoS SLM) with large phase modulation has been thoroughly characterized to operate optimally with several linear phase modulation ranges (π, 2π, 3π, 4π, 6π, and 8π) for an intermediate wavelength of the visible spectrum (λG = 530 nm). For each range, the device response was also measured for two additional wavelengths at the blue and red extremes of the visible spectrum (λB = 476 nm and λR = 647 nm). Multiorder diffractive optical elements, displayed on the LCoS SLM with the appropriate phase modulation range, allowed us to deal with some widely known encoding issues of conventional first-order diffractive lenses such as undersampling and longitudinal chromatic aberration. We designed an achromatic multiorder lens and implemented it experimentally on the SLM. As a result, the residual chromatic aberration reduces to one-third that of the chromatic aberration of a conventional first-order diffractive lens.”

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Publication: Applied Sciences
Issue/Year: Applied Sciences, Volume 9; Number 13; Pages 2592; 2019
DOI: 10.3390/app9132592

Laguerre-Gaussian mode sorter

Author(s):

Fontaine, Nicolas K.; Ryf, Roland; Chen, Haoshuo; Neilson, David T.; Kim, Kwangwoong & Carpenter, Joel

Abstract:

“Exploiting a particular wave property for a particular application necessitates components capable of discriminating in the basis of that property. While spectral or polarisation decomposition can be straightforward, spatial decomposition is inherently more difficult and few options exist regardless of wave type. Fourier decomposition by a lens is a rare simple example of a spatial decomposition of great practical importance and practical simplicity; a two-dimensional decomposition of a beam into its linear momentum components. Yet this is often not the most appropriate spatial basis. Previously, no device existed capable of a two-dimensional decomposition into orbital angular momentum components, or indeed any discrete basis, despite it being a fundamental property in many wave phenomena. We demonstrate an optical device capable of decomposing a beam into a Cartesian grid of identical Gaussian spots each containing a single Laguerre-Gaussian component, using just a spatial light modulator and mirror.”

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Publication: Nature Communications
Issue/Year: Nature Communications, Volume 10; Number 1; 2019
DOI: 10.1038/s41467-019-09840-4

Design, implementation, and study of the high-resolution high-efficiency liquid crystal on silicon spatial light modulator for the telecommunication application in the short-wave infrared spectral band

Author(s): Po-Ju Chen; Philip Engel; Grigory Lazarev; Adam Mazur; H. Paul Urbach

Abstract:

“There are many important applications for phase-only liquid crystal on Silicon-based spatial light modulators (LCOS SLMs). Among the applications, the diffractive beam splitting, beam shaping and beam steering with LCOS SLM are finding more and more use in telecommunication applications (e.g. wavelength selective switch for ROADM, space and mode division multiplexing). However, many effects of LCOS device have to be considered if we want to get high quality output light field. For example, the ideal phase, intensity and polarization distribution in far field are usually deteriorated by the pixelated metal structure and fringing field effects. Thus, the total efficiency is decreased. By using electro-optical and electromagnetic simulation methods, we can properly incorporate the effects that influence the optical performance of LCOS and optimize the design. Furthermore we report the implementation of the high-performance high-resolution LCOS SLM for the telecommunication C- and L-band with the average insertion loss (IL) of less than 0.2 dB, achieved by the reflectivity-enhancement coating on the LCOS backplane. The experimental results on reflectivity, diffraction efficiency, crosstalk and other important parameters are compared with the theoretical predictions.”

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Publication: Optics Express
Issue/Year: SPIE Proceedings Volume 10941, Emerging Liquid Crystal Technologies XIV; 109410E (2019)
doi:10.1117/12.2506825

Holographic Three-Dimensional Virtual Reality and Augmented Reality Display Based on 4K-Spatial Light Modulators

Author(s):

Gao, Hongyue; Xu, Fan; Liu, Jicheng; Dai, Zehang; Zhou, Wen; Li, Suna; Yu, Yingjie & Zheng, Huadong

Abstract:

“In this paper, we propose a holographic three-dimensional (3D) head-mounted display based on 4K-spatial light modulators (SLMs). This work is to overcome the limitation of stereoscopic 3D virtual reality and augmented reality head-mounted display. We build and compare two systems using 2K and 4K SLMs with pixel pitches 8.1 μm and 3.74 μm, respectively. One is a monocular system for each eye, and the other is a binocular system using two tiled SLMs for two eyes. The viewing angle of the holographic head-mounted 3D display is enlarged from 3.8° to 16.4° by SLM tiling, which demonstrates potential applications of true 3D displays in virtual reality and augmented reality.”

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Publication: Applied Sciences
Issue/Year: Applied Sciences, Volume 9; Number 6; Pages 1182; 2019
DOI: 10.3390/app9061182