Non-iterative phase hologram generation with optimized phase modulation

Author(s):

Lizhi Chen, Hao Zhang, Liangcai Cao and Guofan Jin

Abstract:

“A non-iterative algorithm is proposed to generate phase holograms with optimized phase modulation. A quadratic initial phase with continuous distributed spectrum is utilized to iteratively optimize the phase modulation in the reconstruction plane, which can be used as an optimized phase distribution for arbitrary target images. The phase hologram can be calculated directly according to the modulated wave field distribution in the reconstruction plane. Fast generation of the phase holograms can be achieved by this non-iterative implementation, and the avoidance of the random phase modulation helps to suppress the speckle noise. Numerical and
optical experiments have demonstrated that the proposed method can efficiently generate phase holograms with quality reconstructions.”

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Publication: Optics Express

Issue/Year/DOI: Vol. 28, Issue 8, pp. 11380-11392
DOI: 10.1364/OE.391518

High-Resolution Tunable Filter With Flexible Bandwidth and Power Attenuation Based on an LCoS Processor

Author(s):

Yunshu Gao, Genxiang Chen, Xiao Chen, Qian Zhang, Qiao Chen, Ce Zhang, Kai Tian, Zhongwei Tan and Chao Yu

Abstract:

“High-resolution optical filters and wavelength selective switches are the essential components in the current and next-generation dynamic optical networks. A high-resolution programmable filter for telecom application is proposed and experimentally demonstrated based on a 4 k phase-only liquid crystal on silicon (LCoS) spatial light modulator. The tuning resolution, bandwidth, and power attenuation for each wavelength channel can be modulated independently by remote software control. For each channel, the center wavelength is tuned in the step of 7.5 ± 1 pm and the 3 dB bandwidth achieves from 10 GHz to 3 THz. Furthermore, by multi-casting hologram design techniques for an LCoS, the power attenuation is adjusted from 0 dB to 30 dB with the step of 0.1 dB. The insertion loss is less than 6 dB across the entire C-band and 1.8 dB of it can be further improved by adopting an LCoS chip with smaller reflection loss. ”

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Publication: IEEE Photonics Journal

Issue/Year/DOI: Volume: 10 Issue: 6 (2018)
DOI: 10.1109/JPHOT.2018.2876347

On-Chip Detection of Orbital Angular Momentum Beam by Plasmonic Nanogratings

Author(s):

Ji Chen and Xi Chen and Tao Li and Shining Zhu

Abstract:

“Thanks to the unlimited orthogonal states, the orbital angular momentum (OAM) light is widely accepted as a promising carrier for high information multiplexing in optical communications, in which the OAM detection is an important issue. To keep up with the ever‐growing demand for compact integration, here, a plasmonic grating is employed to spatially couple the OAM modes into two separated propagating surface plasmon polariton (SPP) beams with different splitting angles. These splitting angles are found to strongly rely on the topological charges of the incident beams and are insensitive to the specific location of the OAM beam illumination, which provides an intuitive detection of the OAM modes without particular alignment. Besides, a further unidirectional SPP launching from the OAM beam is also achieved by a particular composite grating. With such composite grating, both the topological charge value and sign of OAM beam in a single measurement can be detected. Our results provide a convenient method for alignment‐free OAM detection by a compact device, and would inspire more multiplexing applications in nanophotonics.”

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Publication: Laser & Photonics Reviews

Issue/Year/DOI: Laser & Photonics Reviews Volume 12, Issue 8 (2018)

DOI: 10.1002/lpor.201700331

Non-iterative method for phase retrieval and coherence characterization by focus variation using a fixed star-shaped mask

Author(s):

A. P. Konijnenberg and Xingyuan Lu and Leixin Liu and W. M. J. Coene and Chengliang Zhao and H. P. Urbach

Abstract:

“A novel non-iterative phase retrieval method is proposed and demonstrated with a proof-of-principle experiment. The method uses a fixed specially designed mask and through-focus intensity measurements. It is demonstrated that this method is robust to spatial partial coherence in the illumination, making it suitable for coherent diffractive imaging using spatially partially coherent light, as well as for coherence characterization.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 26, Issue 7, pp. 9332- 9343 (2018)
DOI: 10.1364/OE.26.009332

Tunable third harmonic generation of vortex beams in an optical superlattice

Author(s):

Yu Wu and Rui Ni and Zhou Xu and Yaodong Wu and Xinyuan Fang and Dan Wei and Xiaopeng Hu and Yong Zhang and Min Xiao and Shining Zhu

Abstract:

“We report generation of tunable vortex beams in the blue spectral range, with a 3.3 nm spectral tuning range, by frequency tripling of the near-infrared (IR) wave at around 1.34 um in a LiTaO3 optical superlattice. The nonlinear crystal used in this work has a chirped dual-periodical structure which can provide two expanded reciprocal vectors for tunable performance of the cascaded third harmonic generation (THG). The maximum THG efficiency reaches about 1.4%.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25, Issue 25, pp. 30820- 30826 (2017)
DOI: 10.1364/OE.25.030820

Near-eye light field holographic rendering with spherical waves for wide field of view interactive 3D computer graphics

Author(s):

Liang Shi and Fu-Chung Huang and Ward Lopes and Wojciech Matusik and David Luebke

Abstract:

“Holograms display a 3D image in high resolution and allow viewers to focus freely as if looking through a virtual window, yet computer generated holography (CGH) hasn’t delivered the same visual quality under plane wave illumination and due to heavy computational cost. Light field displays have been popular due to their capability to provide continuous focus cues. However, light field displays must trade off between spatial and angular resolution, and do not model diffraction.

We present a light field-based CGH rendering pipeline allowing for reproduction of high-definition 3D scenes with continuous depth and support of intra-pupil view-dependent occlusion. Our rendering accurately accounts for diffraction and supports various types of reference illuminations for hologram. We avoid under- and over-sampling and geometric clipping effects seen in previous work. We also demonstrate an implementation of light field rendering plus the Fresnel diffraction integral based CGH calculation which is orders of magnitude faster than the state of the art [Zhang et al. 2015], achieving interactive volumetric 3D graphics.

To verify our computational results, we build a see-through, near-eye, color CGH display prototype which enables co-modulation of both amplitude and phase. We show that our rendering accurately models the spherical illumination introduced by the eye piece and produces the desired 3D imagery at the designated depth. We also analyze aliasing, theoretical resolution limits, depth of field, and other design trade-offs for near-eye CGH.”

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Publication: {ACM} Transactions on Graphics

Issue/Year/DOI: ACM Transactions on Graphics, Vol. 36, No. 6, Article 236. (November 2017)
DOI: 10.1145/3130800.3130832