Journals > > Topics > Holography, Gratings, and Diffraction
Holography, Gratings, and Diffraction|34 Article(s)
Holographic multi-waveguide system: towards implementation in wearable sensor technologies
Pamela Stoeva, Tatsiana Mikulchyk, Suzanne Martin, Maria Antonietta Ferrara, Giuseppe Coppola, and Izabela Naydenova
Holographic optical elements (HOEs) are integral to advancements in optical sensing, augmented reality, solar energy harvesting, biomedical diagnostics, and many other fields, offering precise and versatile light manipulation capabilities. This study, to the best of the authors’ knowledge, is the first to design and fabricate an HOE mutli-waveguide system using a thermally and environmentally stable photopolymerizable hybrid sol-gel (PHSG) for sensing applications. Using a 476.5 nm recording wavelength, 60% diffraction efficiency PHSG holographic waveguides of spatial frequency of 1720 lines/mm were successfully fabricated to function as in- and out-couplers at 632.8 nm and 700 nm wavelength, respectively. The waveguides were integrated into a polydimethylsiloxane (PDMS) microfluidic system, guiding excitation light of 632.8 nm wavelength into and extracting fluorescence light signal peaking at 700 nm from a location filled with methylene blue water solution. Further, to demonstrate the potential of the proposed optical system, four holographic waveguides were recorded by peristrophic and angular multiplexing in the same location of the material and the input beam was delivered into four spatially separated channels by total internal reflection in the sol-gel layer, thus, successfully highlighting the capabilities and advantages of HOE waveguides for parallel interrogation of multiple locations in a wearable sensor. This study demonstrates the efficiency and versatility of PHSG-based HOE waveguides, underscoring their potential to enhance photonic device design and performance across various optical applications. Holographic optical elements (HOEs) are integral to advancements in optical sensing, augmented reality, solar energy harvesting, biomedical diagnostics, and many other fields, offering precise and versatile light manipulation capabilities. This study, to the best of the authors’ knowledge, is the first to design and fabricate an HOE mutli-waveguide system using a thermally and environmentally stable photopolymerizable hybrid sol-gel (PHSG) for sensing applications. Using a 476.5 nm recording wavelength, 60% diffraction efficiency PHSG holographic waveguides of spatial frequency of 1720 lines/mm were successfully fabricated to function as in- and out-couplers at 632.8 nm and 700 nm wavelength, respectively. The waveguides were integrated into a polydimethylsiloxane (PDMS) microfluidic system, guiding excitation light of 632.8 nm wavelength into and extracting fluorescence light signal peaking at 700 nm from a location filled with methylene blue water solution. Further, to demonstrate the potential of the proposed optical system, four holographic waveguides were recorded by peristrophic and angular multiplexing in the same location of the material and the input beam was delivered into four spatially separated channels by total internal reflection in the sol-gel layer, thus, successfully highlighting the capabilities and advantages of HOE waveguides for parallel interrogation of multiple locations in a wearable sensor. This study demonstrates the efficiency and versatility of PHSG-based HOE waveguides, underscoring their potential to enhance photonic device design and performance across various optical applications.
Photonics Research
- Publication Date: May. 01, 2025
- Vol. 13, Issue 5, 1428 (2025)
Intelligent tailoring of a broadband orbital angular momentum comb towards efficient optical convolution|Editors' Pick
Shiyun Zhou, Lang Li, Yishu Wang, Liliang Gao, Zhichao Zhang, Chunqing Gao, and Shiyao Fu
Due to the high-dimensional characteristics of photon orbital angular momentum (OAM), a beam can carry multiple OAMs simultaneously thus forming an OAM comb, which has been proved to show significant potential in both classical and quantum photonics. Tailoring broadband OAM combs on demand in a fast and accurate manner is a crucial basis for their application in advanced scenarios. However, obtaining phase-only gratings for the generation of arbitrary desired OAM combs still poses challenges. In this paper, we propose a multi-scale fusion learning U-shaped neural network that encodes a phase-only hologram for tailoring broadband OAM combs on-demand. Proof-of-principle experiments demonstrate that our scheme achieves fast computational speed, high modulation precision, and high manipulation dimensionality, with a mode range of -75 to +75, an average root mean square error of 0.0037, and a fidelity of 85.01%, all achieved in about 30 ms. Furthermore, we utilize the tailored broadband OAM combs in conducting optical convolution calculation, enabling vector convolution for arbitrary discrete functions, showcasing the extended capability of our proposal. This work opens, to our knowledge, new insight for on-demand tailoring of broadband OAM combs, paving the way for further advancements in high-dimensional OAM-based applications. Due to the high-dimensional characteristics of photon orbital angular momentum (OAM), a beam can carry multiple OAMs simultaneously thus forming an OAM comb, which has been proved to show significant potential in both classical and quantum photonics. Tailoring broadband OAM combs on demand in a fast and accurate manner is a crucial basis for their application in advanced scenarios. However, obtaining phase-only gratings for the generation of arbitrary desired OAM combs still poses challenges. In this paper, we propose a multi-scale fusion learning U-shaped neural network that encodes a phase-only hologram for tailoring broadband OAM combs on-demand. Proof-of-principle experiments demonstrate that our scheme achieves fast computational speed, high modulation precision, and high manipulation dimensionality, with a mode range of -75 to +75, an average root mean square error of 0.0037, and a fidelity of 85.01%, all achieved in about 30 ms. Furthermore, we utilize the tailored broadband OAM combs in conducting optical convolution calculation, enabling vector convolution for arbitrary discrete functions, showcasing the extended capability of our proposal. This work opens, to our knowledge, new insight for on-demand tailoring of broadband OAM combs, paving the way for further advancements in high-dimensional OAM-based applications.
Photonics Research
- Publication Date: Apr. 21, 2025
- Vol. 13, Issue 5, 1148 (2025)
Off-axis holographic augmented reality displays with HOE-empowered and camera-calibrated propagation
Xinxing Xia, Daqiang Ma, Xiangyu Meng, Feifan Qu, Huadong Zheng, Yingjie Yu, and Yifan Peng
Holographic near-eye augmented reality (AR) displays featuring tilted inbound/outbound angles on compact optical combiners hold significant potential yet often struggle to deliver satisfying image quality. This is primarily attributed to two reasons: the lack of a robust off-axis-supported phase hologram generation algorithm; and the suboptimal performance of ill-tuned hardware parts such as imperfect holographic optical elements (HOEs). To address these issues, we incorporate a gradient descent-based phase retrieval algorithm with spectrum remapping, allowing for precise hologram generation with wave propagation between nonparallel planes. Further, we apply a camera-calibrated propagation scheme to iteratively optimize holograms, mitigating imperfections arising from the defects in the HOE fabrication process and other hardware parts, thereby significantly lifting the holographic image quality. We build an off-axis holographic near-eye display prototype using off-the-shelf light engine parts and a customized full-color HOE, demonstrating state-of-the-art virtual reality and AR display results. Holographic near-eye augmented reality (AR) displays featuring tilted inbound/outbound angles on compact optical combiners hold significant potential yet often struggle to deliver satisfying image quality. This is primarily attributed to two reasons: the lack of a robust off-axis-supported phase hologram generation algorithm; and the suboptimal performance of ill-tuned hardware parts such as imperfect holographic optical elements (HOEs). To address these issues, we incorporate a gradient descent-based phase retrieval algorithm with spectrum remapping, allowing for precise hologram generation with wave propagation between nonparallel planes. Further, we apply a camera-calibrated propagation scheme to iteratively optimize holograms, mitigating imperfections arising from the defects in the HOE fabrication process and other hardware parts, thereby significantly lifting the holographic image quality. We build an off-axis holographic near-eye display prototype using off-the-shelf light engine parts and a customized full-color HOE, demonstrating state-of-the-art virtual reality and AR display results.
Photonics Research
- Publication Date: Feb. 28, 2025
- Vol. 13, Issue 3, 687 (2025)
Optical polarized orthogonal matrix
Shujun Zheng, Jiaren Tan, Xianmiao Xu, Hongjie Liu, Yi Yang, Xiao Lin, and Xiaodi Tan
Multiplexing technology serves as an effective approach to increase both information storage and transmission capability. However, when exploring multiplexing methods across various dimensions, the polarization dimension encounters limitations stemming from the finite orthogonal combinations. Given that only two mutually orthogonal polarizations are identifiable on the basic Poincaré sphere, this poses a hindrance to polarization modulation. To overcome this challenge, we propose a construction method for the optical polarized orthogonal matrix (OPOM), which is not constrained by the number of orthogonal combinations. Furthermore, we experimentally validate its application in high-dimensional multiplexing of polarization holography. We explore polarization holography technology, capable of recording amplitude, phase, and polarization, for the purpose of recording and selective reconstruction of polarization multi-channels. Our research reveals that, despite identical polarization states, multiple images can be independently manipulated within distinct polarization channels through orthogonal polarization combinations, owing to the orthogonal selectivity among information. By selecting the desired combination of input polarization states, the reconstructed image can be switched with negligible crosstalk. This non-square matrix composed of polarization unit vectors provides prospects for multi-channel information retrieval and dynamic display, with potential applications in optical communication, optical storage, logic devices, anti-counterfeiting, and optical encryption. Multiplexing technology serves as an effective approach to increase both information storage and transmission capability. However, when exploring multiplexing methods across various dimensions, the polarization dimension encounters limitations stemming from the finite orthogonal combinations. Given that only two mutually orthogonal polarizations are identifiable on the basic Poincaré sphere, this poses a hindrance to polarization modulation. To overcome this challenge, we propose a construction method for the optical polarized orthogonal matrix (OPOM), which is not constrained by the number of orthogonal combinations. Furthermore, we experimentally validate its application in high-dimensional multiplexing of polarization holography. We explore polarization holography technology, capable of recording amplitude, phase, and polarization, for the purpose of recording and selective reconstruction of polarization multi-channels. Our research reveals that, despite identical polarization states, multiple images can be independently manipulated within distinct polarization channels through orthogonal polarization combinations, owing to the orthogonal selectivity among information. By selecting the desired combination of input polarization states, the reconstructed image can be switched with negligible crosstalk. This non-square matrix composed of polarization unit vectors provides prospects for multi-channel information retrieval and dynamic display, with potential applications in optical communication, optical storage, logic devices, anti-counterfeiting, and optical encryption.
Photonics Research
- Publication Date: Jan. 28, 2025
- Vol. 13, Issue 2, 373 (2025)
High-order multilayer-coated blazed grating for a high-transmission and high-resolution tender X-ray monochromator/spectrometer
Yeqi Zhuang, Qiushi Huang, Andrey Sokolov, Stephanie Lemke, Zhengkun Liu, Yue Yu, Igor V. Kozhevnikov, Runze Qi, Zhe Zhang, Zhong Zhang, Jens Viefhaus, and Zhanshan Wang
Grating optics lie in the heart of X-ray spectroscopy instruments. The low efficiency and angular dispersion of conventional single-layer-coated gratings significantly limit the transmission and energy resolution of monochromators and spectrometers, particularly in the tender X-ray region (E=1-5 keV). Multilayer-coated blazed gratings (MLBGs) operating at high diffraction orders offer the advantage of achieving both high efficiency and high dispersion simultaneously. Tender X-ray monochromators and spectrometers using different high-order MLBGs have been designed, all demonstrating one to two orders of magnitude higher transmission compared to conventional systems. By employing a 2400 l/mm MLBG at the -4th or -8th diffraction order, the theoretical energy resolution of the instrument is improved by two to three times at 2.5 keV. Two MLBGs operating at the -2nd and -4th orders have been fabricated, showcasing remarkable efficiencies of 34%–12% at 2.5 keV, surpassing that of single-layer-coated gratings by an order of magnitude. Further optimization of manufacturing accuracy can yield even higher efficiencies. The measured angular dispersion agrees well with theoretical predictions, supporting the potential for high resolution. High-order MLBG optics pave the way for a new generation of tender X-ray monochromators/spectrometers that offer both high transmission and high resolution. Grating optics lie in the heart of X-ray spectroscopy instruments. The low efficiency and angular dispersion of conventional single-layer-coated gratings significantly limit the transmission and energy resolution of monochromators and spectrometers, particularly in the tender X-ray region (E=1-5 keV). Multilayer-coated blazed gratings (MLBGs) operating at high diffraction orders offer the advantage of achieving both high efficiency and high dispersion simultaneously. Tender X-ray monochromators and spectrometers using different high-order MLBGs have been designed, all demonstrating one to two orders of magnitude higher transmission compared to conventional systems. By employing a 2400 l/mm MLBG at the -4th or -8th diffraction order, the theoretical energy resolution of the instrument is improved by two to three times at 2.5 keV. Two MLBGs operating at the -2nd and -4th orders have been fabricated, showcasing remarkable efficiencies of 34%–12% at 2.5 keV, surpassing that of single-layer-coated gratings by an order of magnitude. Further optimization of manufacturing accuracy can yield even higher efficiencies. The measured angular dispersion agrees well with theoretical predictions, supporting the potential for high resolution. High-order MLBG optics pave the way for a new generation of tender X-ray monochromators/spectrometers that offer both high transmission and high resolution.
Photonics Research
- Publication Date: Jan. 17, 2025
- Vol. 13, Issue 2, 340 (2025)
Efficient numerical Fresnel diffraction with Gabor frames
David Blinder, Tobias Birnbaum, and Peter Schelkens
Numerical Fresnel diffraction is broadly used in optics and holography in particular. So far, it has been implemented using convolutional approaches, spatial convolutions, or the fast Fourier transform. We propose a new way, to our knowledge, of computing Fresnel diffraction using Gabor frames and chirplets. Contrary to previous techniques, the algorithm has linear-time complexity, does not exhibit aliasing, does not need zero padding, has no constraints on changing shift/resolution/pixel pitch between source and destination planes, and works at any propagation distance. We provide theoretical and numerical analyses, detail the algorithm, and report simulation results with an accelerated GPU implementation. This algorithm may serve as a basis for more flexible, faster, and memory-efficient computer-generated holography methods. Numerical Fresnel diffraction is broadly used in optics and holography in particular. So far, it has been implemented using convolutional approaches, spatial convolutions, or the fast Fourier transform. We propose a new way, to our knowledge, of computing Fresnel diffraction using Gabor frames and chirplets. Contrary to previous techniques, the algorithm has linear-time complexity, does not exhibit aliasing, does not need zero padding, has no constraints on changing shift/resolution/pixel pitch between source and destination planes, and works at any propagation distance. We provide theoretical and numerical analyses, detail the algorithm, and report simulation results with an accelerated GPU implementation. This algorithm may serve as a basis for more flexible, faster, and memory-efficient computer-generated holography methods.
Photonics Research
- Publication Date: Jan. 17, 2025
- Vol. 13, Issue 2, 330 (2025)
Crosstalk-avoided 3D full-color holographic displays enabled by single-cell metasurfaces
Huan Yuan, Wenhao Tang, Zheqiang Zhong, and Bin Zhang
The metasurface possesses great potential in a 3D holographic display due to its powerful ability to manipulate optical fields, ultracompact structure, and extraordinary information capacity. However, the in-plane and interplane crosstalk caused by the coupling between the meta-atoms of the current 3D holographic metasurface limits the quality of the reconstructed image, which has become a significant obstacle to high-performance 3D display applications. Additionally, the interleaved or multilayer design strategy of metasurfaces increases the complexity of structural design and manufacturing, facing challenges in meeting the requirements for miniaturization and low cost-effectiveness. Here, we propose a strategy for a free-space 3D multiplane color holographic multiplex display based on a single-cell metasurface. By utilizing a modified holographic optimization strategy, multiple holographic information is encoded into three mutually independent bases of incident photons and integrated into a metasurface, thereby creating high-quality 3D vectorial metaholography with minimal crosstalk across the visible spectrum. The proposed metasurface has great potential for applications in augmented reality/virtual reality devices, polarization imaging, holographic data encryption, and information storage. The metasurface possesses great potential in a 3D holographic display due to its powerful ability to manipulate optical fields, ultracompact structure, and extraordinary information capacity. However, the in-plane and interplane crosstalk caused by the coupling between the meta-atoms of the current 3D holographic metasurface limits the quality of the reconstructed image, which has become a significant obstacle to high-performance 3D display applications. Additionally, the interleaved or multilayer design strategy of metasurfaces increases the complexity of structural design and manufacturing, facing challenges in meeting the requirements for miniaturization and low cost-effectiveness. Here, we propose a strategy for a free-space 3D multiplane color holographic multiplex display based on a single-cell metasurface. By utilizing a modified holographic optimization strategy, multiple holographic information is encoded into three mutually independent bases of incident photons and integrated into a metasurface, thereby creating high-quality 3D vectorial metaholography with minimal crosstalk across the visible spectrum. The proposed metasurface has great potential for applications in augmented reality/virtual reality devices, polarization imaging, holographic data encryption, and information storage.
Photonics Research
- Publication Date: Jan. 07, 2025
- Vol. 13, Issue 2, 235 (2025)
Phase space framework enables a variable-scale diffraction model for coherent imaging and display
Zhi Li, Xuhao Luo, Jing Wang, Xin Yuan, Dongdong Teng, Qiang Song, and Huigao Duan
The fast algorithms in Fourier optics have invigorated multifunctional device design and advanced imaging technologies. However, the necessity for fast computations limits the widely used conventional Fourier methods, where the image plane has a fixed size at certain diffraction distances. These limitations pose challenges in intricate scaling transformations, 3D reconstructions, and full-color displays. Currently, the lack of effective solutions makes people often resort to pre-processing that compromises fidelity. In this paper, leveraging a higher-dimensional phase space method, a universal framework is proposed for customized diffraction calculation methods. Within this framework, a variable-scale diffraction computation model is established for adjusting the size of the image plane and can be operated by fast algorithms. The model’s robust variable-scale capabilities and its aberration automatic correction capability are validated for full-color holography, and high fidelity is achieved. The tomography experiments demonstrate that this model provides a superior solution for holographic 3D reconstruction. In addition, this model is applied to achieve full-color metasurface holography with near-zero crosstalk, showcasing its versatile applicability at nanoscale. Our model presents significant prospects for applications in the optics community, such as beam shaping, computer-generated holograms (CGHs), augmented reality (AR), metasurface optical elements (MOEs), and advanced holographic head-up display (HUD) systems. The fast algorithms in Fourier optics have invigorated multifunctional device design and advanced imaging technologies. However, the necessity for fast computations limits the widely used conventional Fourier methods, where the image plane has a fixed size at certain diffraction distances. These limitations pose challenges in intricate scaling transformations, 3D reconstructions, and full-color displays. Currently, the lack of effective solutions makes people often resort to pre-processing that compromises fidelity. In this paper, leveraging a higher-dimensional phase space method, a universal framework is proposed for customized diffraction calculation methods. Within this framework, a variable-scale diffraction computation model is established for adjusting the size of the image plane and can be operated by fast algorithms. The model’s robust variable-scale capabilities and its aberration automatic correction capability are validated for full-color holography, and high fidelity is achieved. The tomography experiments demonstrate that this model provides a superior solution for holographic 3D reconstruction. In addition, this model is applied to achieve full-color metasurface holography with near-zero crosstalk, showcasing its versatile applicability at nanoscale. Our model presents significant prospects for applications in the optics community, such as beam shaping, computer-generated holograms (CGHs), augmented reality (AR), metasurface optical elements (MOEs), and advanced holographic head-up display (HUD) systems.
Photonics Research
- Publication Date: Aug. 29, 2024
- Vol. 12, Issue 9, 1937 (2024)
Programmable meta-holography dynamics enabled by grating-modulation
Runlong Rao, Shuai Wan, Zhe Li, Yangyang Shi, and Zhongyang Li
Towards next-generation intelligent display devices, it is urgent to find a cheap and convenient dynamic optical control method. Conventional gratings are widely used as cheap diffractive elements due to their effective optical control capabilities. However, they are limited within multi-function or complex optical modulation due to the lack of accurate control of the amplitude/phase at pixel-level. Here, a metasurface-assisted grating-modulation system is originally proposed to achieve switchable multi-fold meta-holographic dynamics. By incorporating metasurfaces with traditional gratings and tuning their relative coupling positions, the modulation system gains the optical modulation capability to realize complex optical functionalities. Specifically, by varying the grating periods/positions relative to the metasurface, 2–8 holographic image channels are programmed to be dynamically exhibited and switched. The proposed metasurface-assisted grating-modulation approach enjoys cost-effective convenience, strong encoding freedom, and facile operation, which promises programmable optical displays, optical sensors, optical information encryption/storage, etc. Towards next-generation intelligent display devices, it is urgent to find a cheap and convenient dynamic optical control method. Conventional gratings are widely used as cheap diffractive elements due to their effective optical control capabilities. However, they are limited within multi-function or complex optical modulation due to the lack of accurate control of the amplitude/phase at pixel-level. Here, a metasurface-assisted grating-modulation system is originally proposed to achieve switchable multi-fold meta-holographic dynamics. By incorporating metasurfaces with traditional gratings and tuning their relative coupling positions, the modulation system gains the optical modulation capability to realize complex optical functionalities. Specifically, by varying the grating periods/positions relative to the metasurface, 2–8 holographic image channels are programmed to be dynamically exhibited and switched. The proposed metasurface-assisted grating-modulation approach enjoys cost-effective convenience, strong encoding freedom, and facile operation, which promises programmable optical displays, optical sensors, optical information encryption/storage, etc.
Photonics Research
- Publication Date: Jul. 01, 2024
- Vol. 12, Issue 7, 1522 (2024)
Wide-angle digital holography with aliasing-free recording
Rafał Kukołowicz, Izabela Gerej, and Tomasz Kozacki
High-quality wide-angle holographic content is at the heart of the success of near-eye display technology. This work proposes the first digital holographic (DH) system enabling recording wide-angle scenes assembled from objects larger than the setup field of view (FOV), which can be directly replayed without 3D deformation in the near-eye display. The hologram formation in the DH system comprises free space propagation and Fourier transform (FT), which are connected by a rectangular aperture. First, the object wave propagates in free space to the rectangular aperture. Then, the band-limited wavefield is propagated through the single lens toward the camera plane. The rectangular aperture can take two sizes, depending on which DH operates in off-axis or phase-shifting recording mode. An integral part of the DH solution is a numerical reconstruction algorithm consisting of two elements: fringe processing for object wave recovery and wide-angle propagation to the object plane. The second element simulates propagation through both parts of the experimental system. The free space part is a space-limited angular spectrum compact space algorithm, while for propagation through the lens, the piecewise FT algorithm with Petzval curvature compensation is proposed. In the experimental part of the paper, we present the wide-angle DH system with FOV 25°×19°, which allows high-quality recording and reconstruction of large complex scenes. High-quality wide-angle holographic content is at the heart of the success of near-eye display technology. This work proposes the first digital holographic (DH) system enabling recording wide-angle scenes assembled from objects larger than the setup field of view (FOV), which can be directly replayed without 3D deformation in the near-eye display. The hologram formation in the DH system comprises free space propagation and Fourier transform (FT), which are connected by a rectangular aperture. First, the object wave propagates in free space to the rectangular aperture. Then, the band-limited wavefield is propagated through the single lens toward the camera plane. The rectangular aperture can take two sizes, depending on which DH operates in off-axis or phase-shifting recording mode. An integral part of the DH solution is a numerical reconstruction algorithm consisting of two elements: fringe processing for object wave recovery and wide-angle propagation to the object plane. The second element simulates propagation through both parts of the experimental system. The free space part is a space-limited angular spectrum compact space algorithm, while for propagation through the lens, the piecewise FT algorithm with Petzval curvature compensation is proposed. In the experimental part of the paper, we present the wide-angle DH system with FOV 25°×19°, which allows high-quality recording and reconstruction of large complex scenes.
Photonics Research
- Publication Date: May. 01, 2024
- Vol. 12, Issue 5, 1098 (2024)
Topics
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20