Single-shot measurement of the orbital-angular-momentum spectrum of light.

Author(s):

Kulkarni, Girish and Sahu, Rishabh and Magaña-Loaiza, Omar S. and Boyd, Robert W. and Jha, Anand K.

Abstract:

“The existing methods for measuring the orbital-angular-momentum (OAM) spectrum suffer from issues such as poor efficiency, strict interferometric stability requirements, and too much loss. Furthermore, most techniques inevitably discard part of the field and measure only a post-selected portion of the true spectrum. Here, we propose and demonstrate an interferometric technique for measuring the true OAM spectrum of optical fields in a single-shot manner. Our technique directly encodes the OAM-spectrum information in the azimuthal intensity profile of the output interferogram. In the absence of noise, the spectrum can be fully decoded using a single acquisition of the output interferogram, and, in the presence of noise, acquisition of two suitable interferograms is sufficient for the purpose. As an important application of our technique, we demonstrate measurements of the angular Schmidt spectrum of the entangled photons produced by parametric down-conversion and report a broad spectrum with the angular Schmidt number 82.1.”

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Publication: Nature Communications

Issue/Year/DOI: Nature Communicationsvolume 8, Article number: 1054 (2017)
DOI: 10.1038/s41467-017-01215-x

Single camera shot interferenceless coded aperture correlation holography

Author(s):

Mani Ratnam Rai and A. Vijayakumar and Joseph Rosen

Abstract:

“We propose a new scheme for recording an incoherent digital hologram by a single camera shot. The method is based on a motionless, interferenceless, coded aperture correlation holography for 3D imaging. Two random-like coded phase masks (CPMs) are synthesized using the Gerchberg–Saxton algorithm with two different initial random phase profiles. The two CPMs are displayed side by side and used as the system aperture. Light from a pinhole is introduced into the system, and two impulse responses are recorded corresponding to the two CPMs. The two impulse responses are subtracted, and the resulting intensity profile is used as a reconstructing hologram. A library of reconstructing holograms is created corresponding to all possible axial locations. Following the above training stage, an object is placed within the axial limits of the library, and the intensity patterns of a single shot, corresponding to the same two CPMs, are recorded under identical conditions to generate the object hologram. The image of the object at any plane is reconstructed by a cross-correlation between the object hologram and the corresponding reconstructing hologram from the library.”

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Publication: Optics Letters

Issue/Year/DOI: Optics Letters Vol. 42, Issue 19, pp. 3992-3995 (2017)

DOI: 10.1364/OL.42.003992

 

Superresolution far-field imaging of complex objects using reduced superoscillating ripples

Author(s):

Xiao Han Dong and Alex M. H. Wong and Minseok Kim and George V. Eleftheriades

Abstract:

“Superoscillation is a phenomenon where a wave oscillates locally faster than its highest Fourier component. While previous reports have shown attractive possibilities for a superoscillation-based far-field superresolution imaging device, it has also been recognized that a high-energy “sideband” region coexists with the superresolution features. This sideband causes strong restrictions and necessitates trade-offs in achievable resolution, viewing area, and sensitivity of the imaging device. In this work, we introduce a new class of superoscillation waveform—which consists of a diffraction-limited hotspot surrounded by low-energy superoscillating sidelobe ripples. This waveform alleviates the aforementioned trade-off and enables superresolution imaging for complex objects over a larger viewing area while maintaining a practical level of sensitivity. Using this waveform as the point spread function of an imaging system, we demonstrate the successful superresolution of Latin letters without performing scanning and/or post-processing operations.”

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Publication: Optica

Issue/Year/DOI: Optica, Vol. 4, Issue 9, pp. 1126-1133 (2017)
DOI: 10.1364/OPTICA.4.001126

Silver Nanowires for Reconfigurable Bloch Surface Waves.

Author(s):

Zhang, Douguo and Wang, Ruxue and Xiang, Yifeng and Kuai, Yan and Kuang, Cuifang and Badugu, Ramachandram and Xu, Yingke and Wang, Pei and Ming, Hai and Liu, Xu and Lakowicz, Joseph R.

Abstract:

“The use of a single silver nanowire as a flexible coupler to transform a free space beam into a Bloch surface wave propagating on a dielectric multilayer is proposed. Based on Huygens ‘Principle, when a Gaussian beam is focused onto a straight silver nanowire, a Bloch surface wave is generated and propagates perpendicular to the nanowire. By curving the silver nanowire, the surface wave can be focused. Furthermore, the spatial phase of the incident laser beam can be actively controlled with the aid of a spatial light modulator, resulting in the reconfigurable or dynamically controlled Bloch surface waves. The low cost of the chemically synthesized silver nanowires and the high flexibility with regard to tuning the spatial phase of the incident light make this approach very promising for various applications including optical micromanipulation, fluorescence imaging, and sensing.”

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Publication: ACS Nano

Issue/Year/DOI:  ACS Nano, 2017, 11 (10), pp 10446–10451
DOI: 10.1021/acsnano.7b05638

Programmable Vector Mode Multiplexer

Author(s): N. K. Fontaine and H. Chen and R. Ryf and D. Neilson and J. C. Alvarado and J. van Weerdenburg and R. Amezcua-Correa and C. Okonkwo and J. Carpenter

Abstract:

“We demonstrate a programmable vector mode multiplexer using a low-loss spatial light phase modulator that can multiplex 10 modes. It is reconfigured to generate modes for multi-mode fiber and modes with arbitrary polarization including linear, radial, and azimuthal.”

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Publication: 2017 European Conference on Optical Communication (ECOC)

Issue/Year/DOI: 2017 European Conference on Optical Communication (ECOC)
DOI: 10.1109/ECOC.2017.8346099

Dynamic three-dimensional multifocal spots in high numerical-aperture objectives

Author(s):

Linwei Zhu and Rui Yang and Dawei Zhang and Junjie Yu and Jiannong Chen

Abstract:

“Multifocal spots in high numerical-aperture (NA) objectives has emerged as a rapid, parallel, and multi-location method in a multitude of applications. However, the typical method used for forming three-dimensional (3D) multifocal spots based on iterative algorithms limits the potential applications. We demonstrate a non-iterative method using annular subzone phases (ASPs) that are composed of many annular subareas in which phase-only distributions with different 3D displacements are filled. The dynamic 3D multifocal spots with controllable position of each focal spot in the focal volume of the objective are created using the ASPs. The experimental results of such dynamic tunable 3D multifocal spots offer the possibility of versatile process in laser 3D fabrication, optical trapping, and fast focusing scanned microscopic imaging.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25, Issue 20, pp. 24756- 24766 (2018)
DOI: 10.1364/OE.25.024756

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

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/DOI: Optics Letters Vol. 42, Issue 16, pp. 3205-3208 (2017)

DOI: 10.1364/OL.42.003205

 

Holographic near-eye displays for virtual and augmented reality

Author(s):

Maimone, Andrew and Georgiou, Andreas and Kollin, Joel S

Abstract:
“We present novel designs for virtual and augmented reality near-eye displays based on phase-only holographic projection. Our approach is built on the principles of Fresnel holography and double phase amplitude encoding with additional hardware, phase correction factors, and spatial light modulator encodings to achieve full color, high contrast and low noise holograms with high resolution and true per-pixel focal control. We provide a GPU-accelerated implementation of all holographic computation that integrates with the standard graphics pipeline and enables real-time (≥90 Hz) calculation directly or through eye tracked approximations. A unified focus, aberration correction, and vision correction model, along with a user calibration process, accounts for any optical defects between the light source and retina. We use this optical correction ability not only to x minor aberrations but to enable truly compact, eyeglasses-like displays with wide elds of view (80◦) that would be inaccessible through conventional means. All functionality is evaluated across a series of hardware prototypes; we discuss remaining challenges to incorporate all features into a single device.”

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Publication: ACM Transactions on Graphics (TOG)

Issue/Year/DOI: ACM Transactions on Graphics, Vol. 36, No. 4, Article 85. (July 2017)
DOI: 10.1145/3072959.3073624