Dynamic 2D implementation of 3D diffractive optics

Author(s):

Haiyan Wang and Rafael Piestun

Abstract:

“Volumetric computer-generated diffractive optics offer advantages over planar 2D implementations, including the generation of space-variant functions and the multiplexing of information in space or frequency domains. Unfortunately, despite remarkable progress, fabrication of high volumetric space-bandwidth micro- and nanostructures
is still in its infancy. Furthermore, existing 3D diffractive optics implementations are static while programmable volumetric spatial light modulators (SLMs) are still years or decades away. In order to address these shortcomings, we propose the implementation of volumetric diffractive optics equivalent functionality via cascaded
planar elements. To illustrate the principle, we design 3D diffractive optics and implement a two-layer continuous phase-only design on a single SLM with a folded setup. The system provides dynamic and efficient multiplexing capability. Numerical and experimental results show this approach improves system performance such as diffraction
efficiency, spatial/spectral selectivity, and number of multiplexing functions relative to 2D devices while providing dynamic large space-bandwidth relative to current static volume diffractive optics. The limitations and capabilities of dynamic 3D diffractive optics are discussed.”

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Publication: Optica

Issue/Year/DOI: Optica Volume 5, Issues 10
DOI: doi.org/10.1364/OPTICA.5.001220

Deep speckle correlation: a deep learning approach toward scalable imaging through scattering media

Author(s):

Yunzhe Li and Yujia Xue and Lei Tian

Abstract:

“Imaging through scattering is an important yet challenging problem. Tremendous progress has been made by exploiting the deterministic input–output “transmission matrix” for a fixed medium. However, this “one-to-one” mapping is highly susceptible to speckle decorrelations – small perturbations to the scattering medium lead to model errors and severe degradation of the imaging performance. Our goal here is to develop a new framework that is highly scalable to both medium perturbations and measurement requirement. To do so, we propose a statistical “one-to-all” deep learning (DL) technique that encapsulates a wide range of statistical variations for the model to be resilient to speckle decorrelations. Specifically, we develop a convolutional neural network (CNN) that is able to learn the statistical information contained in the speckle intensity patterns captured on a set of diffusers having the same macroscopic parameter. We then show for the first time, to the best of our knowledge, that the trained CNN is able to generalize and make high-quality object predictions through an entirely different set of diffusers of the same class. Our work paves the way to a highly scalable DL approach for imaging through scattering media.”

Link to Publications Page

Publication: Optica

Issue/Year/DOI: Optica Volume 5, Issue 10 pp. 1181-1190 (2018)
DOI: 10.1364/OPTICA.5.001181

Measuring orbital angular momentums of light based on petal interference patterns

Author(s):

Shengzhe Pan and Chunying Pei and Shuang Liu and Jin Wei and Di Wu and Zhanou Liu and Yaling Yin and Yong Xia and Jianping Yin

Abstract:

“We demonstrate an interferometric method to measure the topological charges of the vortex beams carrying orbital angular momentums (OAMs). The petal interference patterns are generated by combining modulated vortex beams and an unmodulated incident Gaussian beam reflected by a spatial light modulator. The number of petals is in agreement with the value of OAM that the modulated beam carries, by which we analyze the characteristic of interference patterns of integer OAM beams, including intensity profiles, phase profiles, and hologram structures. We also uncover the principle of how radial parameter l influences the hollow radius of OAM beams. Beams carrying non-integer orbital angular momentums are visualized with our method, from which we observe the evolution of a speckle generated by the decimal part of holograms. A kind of hologram is designed to prove that the petal near the singularity line is separated owing to the diffraction enhancement. All the experiment results agree well with the simulated results.”

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Publication: OSA Continuum
Issue/Year/DOI: OSA Continuum Volume 1, Issue 2 (2018)
DOI: 10.1364/OSAC.1.000451

Optical see-through holographic near-eye-display with eyebox steering and depth of field control

Author(s):
Jae-Hyeung Park and Seong-Bok Kim

Abstract:

“We propose an optical see-through holographic near-eye-display that can control the depth of field of individual virtual three-dimensional image and replicate the eyebox with dynamic steering. For optical see-through capability and eyebox duplication, a holographic optical element is used as an optical combiner where it functions as multiplexed tilted concave mirrors forming multiple copies of the eyebox. Fo1r depth of field control and eyebox steering, computer generated holograms of three-dimensional objects are synthesized with different ranges of angular spectrum. In optical experiment, it has been confirmed that the proposed system can present always-focused images with large depth of field and three-dimensional images at different distances with shallow depth of field at the same time without any time-multiplexing.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express Volume 26, Issue 21
DOI: 10.1364/oe.26.027076

Self-healing high-dimensional quantum key distribution using hybrid spin-orbit Bessel states

Author(s):

Isaac Nape, Eileen Otte, Adam Vallés, Carmelo Rosales-Guzmán, Filippo Cardano, Cornelia Denz, and Andrew Forbes

Abstract:

“Using spatial modes for quantum key distribution (QKD) has become highly topical due to their infinite dimensionality, promising high information capacity per photon. However, spatial distortions reduce the feasible secret key rates and compromise the security of a quantum channel. In an extreme form such a distortion might be a physical obstacle, impeding line-of-sight for free-space channels. Here, by controlling the radial degree of freedom of a photon’s spatial mode, we are able to demonstrate hybrid high-dimensional QKD through obstacles with self-reconstructing single photons. We construct high-dimensional mutually unbiased bases using spin-orbit hybrid states that are radially modulated with a non-diffracting Bessel-Gaussian (BG) profile, and show secure transmission through partially obstructed quantum links. Using a prepare-measure protocol we report higher quantum state self-reconstruction and information retention for the non-diffracting BG modes as compared to Laguerre-Gaussian modes, obtaining a quantum bit error rate (QBER) that is up to 3× lower. This work highlights the importance of controlling the radial mode of single photons in quantum information processing and communication as well as the advantages of QKD with hybrid states.”

Link to Publications Page

Publication: Optics Express

Issue/Year/DOI: Optics Express Volume 26, Issue 21
DOI: 10.1364/OE.26.026946