Journal Description
Photonics
Photonics
is an international, scientific, peer-reviewed, open access journal on the science and technology of optics and photonics, published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.5 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journal: Optics.
Impact Factor:
2.4 (2022);
5-Year Impact Factor:
2.4 (2022)
Latest Articles
Exploring the Origin of Lissajous Geometric Modes from the Ray Tracing Model
Photonics 2024, 11(5), 456; https://doi.org/10.3390/photonics11050456 (registering DOI) - 13 May 2024
Abstract
In this paper, we use the geometric optics and discuss the path of laser beam in a simple laser (concave-plano) cavity with the birefringence crystal. In specific lengths of the laser cavity, we can observe various types of Lissajous-like structural laser modes that
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In this paper, we use the geometric optics and discuss the path of laser beam in a simple laser (concave-plano) cavity with the birefringence crystal. In specific lengths of the laser cavity, we can observe various types of Lissajous-like structural laser modes that can be simulated using our ray tracing model. At the end of this paper, we provide an adjusted ABCD matrix. With the adjusted ABCD matrix and iterative calculation, we can obtain the 3D trajectories which are similar to the experimental results. These structural laser modes can be realized by a solid-state laser with off-axis pumping. From the comparison between the experimental data and the numerical data, we clarify the relationship between the 3D Lissajous-like structural laser modes and ray trajectory in the laser cavity.
Full article
(This article belongs to the Special Issue Emerging Topics in Structured Light)
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Open AccessArticle
Analytical Model of Point Spread Function under Defocused Degradation in Diffraction-Limited Systems: Confluent Hypergeometric Function
by
Feijun Song, Qiao Chen, Xiongxin Tang and Fanjiang Xu
Photonics 2024, 11(5), 455; https://doi.org/10.3390/photonics11050455 (registering DOI) - 13 May 2024
Abstract
In recent years, optical systems near the diffraction limit have been widely used in high-end applications. Evidently, an analytical solution of the point spread function (PSF) will help to enhance both understanding and dealing with the imaging process. This paper analyzes the Fresnel
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In recent years, optical systems near the diffraction limit have been widely used in high-end applications. Evidently, an analytical solution of the point spread function (PSF) will help to enhance both understanding and dealing with the imaging process. This paper analyzes the Fresnel diffraction of diffraction-limited optical systems in defocused conditions. For this work, an analytical solution of the defocused PSF was obtained using the series expansion of the confluent hypergeometric functions. The analytical expression of the defocused optical transfer function is also presented herein for comparison with the PSF. Additionally, some characteristic parameters for the PSF are provided, such as the equivalent bandwidth and the Strehl ratio. Comparing the PSF obtained using the fast Fourier transform algorithm of an optical system with known, detailed parameters to the analytical solution derived in this paper using only the typical parameters, the root mean square errors of the two methods were found to be less than 3% in the weak and medium defocus range. The attractive advantages of the universal model, which is independent of design details, objective types, and applications, are discussed.
Full article
(This article belongs to the Special Issue Emerging Topics in High-Power Laser and Light–Matter Interactions)
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Open AccessArticle
Dual-Polarization Conversion and Coding Metasurface for Wideband Radar Cross-Section Reduction
by
Saima Hafeez, Jianguo Yu, Fahim Aziz Umrani, Yibo Huang, Wang Yun and Muhammad Ishfaq
Photonics 2024, 11(5), 454; https://doi.org/10.3390/photonics11050454 (registering DOI) - 11 May 2024
Abstract
Modern stealth application systems require integrated meta-devices to operate effectively and have gained significant attention recently. This research paper proposes a 1-bit coding metasurface (CM) design. The fundamental component of the proposed CM is integrated to convert linearly polarized incoming electromagnetic waves into
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Modern stealth application systems require integrated meta-devices to operate effectively and have gained significant attention recently. This research paper proposes a 1-bit coding metasurface (CM) design. The fundamental component of the proposed CM is integrated to convert linearly polarized incoming electromagnetic waves into their orthogonal counterpart within frequency bands of 12.37–13.03 GHz and 18.96–32.37 GHz, achieving a polarization conversion ratio exceeding 99%. Furthermore, it enables linear-to-circular polarization conversion from 11.80 to 12.29, 13.17 to 18.44, and 33.33 to 40.35 GHz. A second element is produced by rotating a fundamental component by 90°, introducing a phase difference of π (pi) between them. Both elements are arranged in an array using a random aperiodic coding sequence to create a 1-bit CM for reducing the radar cross-section (RCS). The planar structure achieved over 10 dB RCS reduction for polarized waves in the frequency bands of 13.1–13.8 GHz and 20.4–30.9 GHz. A prototype was fabricated and tested, with the experimental results showing a good agreement with the simulated outcomes. The proposed design holds potential applications in radar systems, reflector antennas, stealth technologies, and satellite communication.
Full article
(This article belongs to the Special Issue Advanced Photonics Metamaterials and Metasurfaces: Science and Applications)
Open AccessArticle
Ghost Fringe Suppression by Modifying the f-Number of the Diverger Lens for the Interferometric Measurement of Catadioptric Telescopes
by
Yi-Kai Huang and Cheng-Huan Chen
Photonics 2024, 11(5), 453; https://doi.org/10.3390/photonics11050453 (registering DOI) - 11 May 2024
Abstract
A high-precision catadioptric telescope such as a space-borne telescope is usually tested with interferometer to check the optical quality in assembly. The coarse and fine alignment of the telescope are mainly based on the information from the coordinate measuring machine and the fringe
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A high-precision catadioptric telescope such as a space-borne telescope is usually tested with interferometer to check the optical quality in assembly. The coarse and fine alignment of the telescope are mainly based on the information from the coordinate measuring machine and the fringe pattern of the interferometer, respectively. In addition, further fine-tuning can be achieved according to the variation in wavefront error and Zernike data. The issue is that the vast majority of the catadioptric telescopes contain plural lens surfaces which could produce unwanted ghost fringes, disturbing the wavefront measurement. Technically, off-axis installation to shift away ghost fringes from central interferogram could be acceptable in some cases. Nevertheless, in this paper, the source of ghost fringe in interferometric measurement for catadioptric telescopes is investigated with light path simulation, and a solution of reducing the f-number of the diverger lens is proposed to eliminate the ghost fringe disturbance. Both simulation and experimental results verify the effectiveness of the proposed concept.
Full article
(This article belongs to the Special Issue Optical Systems for Astronomy)
Open AccessArticle
Flow Field Estimation with Distortion Correction Based on Multiple Input Deep Convolutional Neural Networks and Hartmann–Shack Wavefront Sensing
by
Zeyu Gao, Xinlan Ge, Licheng Zhu, Shiqing Ma, Ao Li, Lars Büttner, Jürgen Czarske and Ping Yang
Photonics 2024, 11(5), 452; https://doi.org/10.3390/photonics11050452 (registering DOI) - 11 May 2024
Abstract
The precise estimation of fluid motion is critical across various fields, including aerodynamics, hydrodynamics, and industrial fluid mechanics. However, refraction at complex interfaces in the light path can cause image deterioration and lead to severe measurement errors if the aberration changes with time,
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The precise estimation of fluid motion is critical across various fields, including aerodynamics, hydrodynamics, and industrial fluid mechanics. However, refraction at complex interfaces in the light path can cause image deterioration and lead to severe measurement errors if the aberration changes with time, e.g., at fluctuating air–water interfaces. This challenge is particularly pronounced in technical energy conversion processes such as bubble formation in electrolysis, droplet formation in fuel cells, or film flows. In this paper, a flow field estimation algorithm that can perform the aberration correction function is proposed, which integrates the flow field distribution estimation algorithm based on the Particle Image Velocimetry (PIV) technique and the novel actuator-free adaptive optics technique. Two different multi-input convolutional neural network (CNN) structures are established, with two frames of distorted PIV images and measured wavefront distortion information as inputs. The corrected flow field results are directly output, which are divided into two types based on different network structures: dense estimation and sparse estimation. Based on a series of models, a corresponding dataset synthesis model is established to generate training datasets. Finally, the algorithm performance is evaluated from different perspectives. Compared with traditional algorithms, the two proposed algorithms achieves reductions in the root mean square value of velocity residual error by 84% and 89%, respectively. By integrating both flow field measurement and novel adaptive optics technique into deep CNNs, this method lays a foundation for future research aimed at exploring more intricate distortion phenomena in flow field measurement.
Full article
(This article belongs to the Special Issue Challenges and Future Directions in Adaptive Optics Technology)
Open AccessArticle
Improved DeepLabV3+ Network Beacon Spot Capture Methods
by
Jun Liu, Xiaolong Ni, Xin Yu and Cong Li
Photonics 2024, 11(5), 451; https://doi.org/10.3390/photonics11050451 (registering DOI) - 11 May 2024
Abstract
In long-range laser communication, adaptive optics tracking systems are often used to achieve high-precision tracking. When recognizing beacon spots for tracking, the traditional threshold segmentation method is highly susceptible to segmentation errors in the face of interference. In this study, an improved DeepLabV3+
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In long-range laser communication, adaptive optics tracking systems are often used to achieve high-precision tracking. When recognizing beacon spots for tracking, the traditional threshold segmentation method is highly susceptible to segmentation errors in the face of interference. In this study, an improved DeepLabV3+ network is designed for fast and accurate capture of beacon spots in complex situations. In order to speed up the inference process, the backbone of the model was rewritten as MobileNetV2. This study improves the ASPP (Atrous Spatial Pyramid Pooling) module by splicing and fusing the outputs and inputs of its different layers. Meanwhile, the original convolution in the module is rewritten as a depthwise separable convolution with a dilation rate to reduce the computational burden. CBAM (Convolutional Block Attention Module) is applied, and the focus loss function is introduced during training. The network yields an accuracy of 98.76% mean intersection over union on self-constructed beacon spot dataset, and the segmentation consumes only 12 milliseconds, which realizes the fast and high-precision capturing of beacon spots.
Full article
(This article belongs to the Special Issue Challenges and Future Directions in Adaptive Optics Technology)
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Open AccessArticle
Crystal ZnGeP2 for Nonlinear Frequency Conversion: Physical Parameters, Phase-Matching and Nonlinear Properties: Revision
by
Sergey G. Grechin and Ilyia A. Muravev
Photonics 2024, 11(5), 450; https://doi.org/10.3390/photonics11050450 (registering DOI) - 11 May 2024
Abstract
The article presents a comparative analysis of published data for the physical parameters of the ZGP (ZnGeP2) crystal, its nonlinear and phase-matching properties, and functional capabilities for all frequency conversion processes (harmonics, sum and difference frequencies, and parametric generation). At the
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The article presents a comparative analysis of published data for the physical parameters of the ZGP (ZnGeP2) crystal, its nonlinear and phase-matching properties, and functional capabilities for all frequency conversion processes (harmonics, sum and difference frequencies, and parametric generation). At the first time, the possibilities for obtaining the temperature-noncritical processes for some combinations of wavelengths are shown.
Full article
(This article belongs to the Special Issue Advanced Solid-State and Fiber Mid-IR Lasers: Novel Materils, Components, Systems and Applications)
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Open AccessCommunication
Gain-Switched Er-Doped Fluoride Fiber Laser at ~3.75 μm
by
Lu Zhang, Shijie Fu, Quan Sheng, Xuewen Luo, Junxiang Zhang, Wei Shi, Qiang Fang and Jianquan Yao
Photonics 2024, 11(5), 449; https://doi.org/10.3390/photonics11050449 (registering DOI) - 11 May 2024
Abstract
We demonstrate a pulsed Er-doped ZBLAN fiber laser operating at 3.75 μm based on the gain-switching scheme. A diffraction grating is introduced as a wavelength selection component to enable stable lasing in this long-wavelength region that deviates from the emission peak of 4
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We demonstrate a pulsed Er-doped ZBLAN fiber laser operating at 3.75 μm based on the gain-switching scheme. A diffraction grating is introduced as a wavelength selection component to enable stable lasing in this long-wavelength region that deviates from the emission peak of 4F9/2→4I9/2 transition in Er3+. Different from the conventional gain-switching behavior where the pulse repetition frequency of the output laser is same as the that of the pump, the gain-switched laser demonstrated here shows a variable pulse repetition frequency, which accounts for 1/n (n = 4, 3, 2) of the pump pulse repetition frequency, in response to the 1950 nm pump power. The output pulse characteristics, including average output power, repetition frequency, pulse duration, and peak power, are investigated in detail. Over 200 mW average output power at 3.75 μm was obtained at 12 W of 1950 nm pump power. This work demonstrates that the Er-doped ZBLAN fiber laser, in combination with gain-switched scheme, is a feasible and promising approach to generate powerful pulsed emission > 3.7 μm.
Full article
(This article belongs to the Special Issue Research on Rare-Earth-Doped Fiber Lasers)
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Open AccessArticle
Penrose Scattering in Quantum Vacuum
by
José Tito Mendonça
Photonics 2024, 11(5), 448; https://doi.org/10.3390/photonics11050448 (registering DOI) - 10 May 2024
Abstract
This paper considers the scattering of a probe laser pulse by an intense light spring in a QED vacuum. This new scattering configuration can be seen as the vacuum equivalent to the process originally associated with the scattering of light by a rotating
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This paper considers the scattering of a probe laser pulse by an intense light spring in a QED vacuum. This new scattering configuration can be seen as the vacuum equivalent to the process originally associated with the scattering of light by a rotating black hole, which is usually called Penrose superradiance. Here, the rotating object is an intense laser beam containing two different components of orbital angular momentum. Due to these two components having slightly different frequencies, the energy profile of the intense laser beam rotates with an angular velocity that depends on the frequency difference. The nonlinear properties of a quantum vacuum are described by a first-order Euler–Heisenberg Lagrangian. It is shown that in such a configuration, nonlinear photon–photon coupling leads to scattered radiation with frequency shift and angular dispersion. These two distinct properties, of frequency and propagation direction, could eventually be favorable for possible experimental observations. In principle, this new scattering configuration can also be reproduced in a nonlinear optical medium.
Full article
(This article belongs to the Special Issue Photon-Photon Collision Using Extreme Lasers)
Open AccessReview
Research Progress on Femtosecond Laser Poling of Ferroelectrics
by
Yan Sheng, Xin Chen, Tianxiang Xu, Shan Liu, Ruwei Zhao and Wieslaw Krolikowski
Photonics 2024, 11(5), 447; https://doi.org/10.3390/photonics11050447 (registering DOI) - 10 May 2024
Abstract
Ferroelectric domain engineering has wide applications in optical and electronic industries. Compared with traditional electric field poling, femtosecond laser poling has many advantages, such as higher fabrication resolution, 3D engineering applicability, and lower costs of production. In this review, the recent research progress
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Ferroelectric domain engineering has wide applications in optical and electronic industries. Compared with traditional electric field poling, femtosecond laser poling has many advantages, such as higher fabrication resolution, 3D engineering applicability, and lower costs of production. In this review, the recent research progress on ferroelectric domain engineering with femtosecond laser pulses is presented. We show the latest results, including complex domain structures fabricated in various kinds of ferroelectric crystals, and discuss the influence of laser poling parameters and conditions on the morphologies of inverted domains and their physical mechanisms. The technical challenges to overcome in future are also briefly discussed.
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Open AccessArticle
Optimized Wide-Angle Metamaterial Edge Filters: Enhanced Performance with Multi-Layer Designs and Anti-Reflection Coatings
by
Baidong Wu, James N. Monks, Liyang Yue, Andrew Hurst and Zengbo Wang
Photonics 2024, 11(5), 446; https://doi.org/10.3390/photonics11050446 (registering DOI) - 10 May 2024
Abstract
This study presents a systematic optimization of wide-angle metamaterial long-pass (LP) edge filters based on silicon nanospheres (SiNP). Multi-layered configurations incorporating SiNP-meta-films and anti-reflection coating (ARC) elements not previously considered in the literature are explored to enhance their filter performance in both stop
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This study presents a systematic optimization of wide-angle metamaterial long-pass (LP) edge filters based on silicon nanospheres (SiNP). Multi-layered configurations incorporating SiNP-meta-films and anti-reflection coating (ARC) elements not previously considered in the literature are explored to enhance their filter performance in both stop and pass bands. This research has successfully developed an accurate model for the effective refractive index using Kramers–Kronig relations, enabling the use of classical thin-film design software for rapid device performance optimization, which is verified by full-wave numerical software. This systematic optimization has produced highly efficient, near-shift-free long-pass metamaterial filters, evidenced by their high optical density (OD = 2.55) and low spectral shift across a wide angular range (0°–60°). These advancements herald the development of high-efficiency metamaterial optical components suitable for a variety of applications that require a consistent performance across diverse angles of incidence.
Full article
(This article belongs to the Special Issue Emerging Trends in Metamaterials and Metasurfaces Research)
Open AccessArticle
Polarization-Based Reflection Suppression Method and Its Application to Target Detection
by
Jin Duan, Jialin Wang, Qiang Fu, Guofang Xie, Suxin Mo and Ruisen Fang
Photonics 2024, 11(5), 445; https://doi.org/10.3390/photonics11050445 - 10 May 2024
Abstract
Active illumination light becomes strongly reflective interference light after specular reflection. It causes saturation in some areas of the image during target detection, resulting in the inability to recognize detailed target feature information. This greatly limits the application of active illumination detection. Based
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Active illumination light becomes strongly reflective interference light after specular reflection. It causes saturation in some areas of the image during target detection, resulting in the inability to recognize detailed target feature information. This greatly limits the application of active illumination detection. Based on the Mueller matrix analysis of the difference in polarization characteristics between the background specular reflected light and the target reflected light, we propose a reflection suppression method based on orthogonal polarization imaging. The method employs a polarization modulation strategy in a bidirectional manner between the light source and the detector. First, the polarization information difference is amplified by active polarized illumination between the background specular reflected light and the target reflected light. Then, the target recovery is achieved by suppressing the background specular reflected light through the polarized orthogonal imaging method. Meanwhile, this method can also be used for moving target detection. The experimental results show that the reflection suppression method of orthogonal polarization imaging can effectively suppress the interference of specular reflection on the target image. Additionally, it can reduce the problems of missed and false detection that occurs in moving target detection and improve the active illumination detection effect.
Full article
(This article belongs to the Section Optical Interaction Science)
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Open AccessArticle
Individual Tuning of Directional Emission and Luminance of a Quantum Emitter in a Composite Plasmonic Antenna
by
Chaonuo Xin, Yuming Huang, Renpu Li and Yong Ma
Photonics 2024, 11(5), 444; https://doi.org/10.3390/photonics11050444 - 10 May 2024
Abstract
High directional emission and high radiative quantum efficiency are strongly needed when moving a single optical nano-emitter (such as a quantum dot) into the practical realm. However, a typical optical nano-emitter struggles to meet the requirements above, which limits its practical applications in
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High directional emission and high radiative quantum efficiency are strongly needed when moving a single optical nano-emitter (such as a quantum dot) into the practical realm. However, a typical optical nano-emitter struggles to meet the requirements above, which limits its practical applications in next-generation nano-photonic devices such as single-photon sources. Here, to achieve these features simultaneously, we propose and theoretically investigate a composite plasmonic antenna consisting of a hemispherical solid immersion lens (SIL) and a bowtie plasmonic nano-antenna, wherein a high directional emission of 10° and 2.5 × 103 of Purcell factor have both been enabled. Moreover, we find that directionality and the Purcell factor can be manipulated independently in our antenna, which provides a novel platform for the optimization of single-photon sources.
Full article
(This article belongs to the Special Issue Optical Quantum System)
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Open AccessArticle
Research on Dual-Grating Spacing Calibration Method Based on Multiple Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise Combined with Hilbert Transform
by
Yanzhen Zhu, Jiayuan Sun, Yuqing Guan, Liqin Liu, Chuangwei Guo, Yujie Zhang, Jun Wan and Lihua Lei
Photonics 2024, 11(5), 443; https://doi.org/10.3390/photonics11050443 - 10 May 2024
Abstract
The paper proposes a method for the calibration of spacing in dual-grating based on Multiple Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN) combined with Hilbert Transform (HT), referred to as Multiple ICEEMDAN-HT. This method addresses the potential impact of nonlinear
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The paper proposes a method for the calibration of spacing in dual-grating based on Multiple Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN) combined with Hilbert Transform (HT), referred to as Multiple ICEEMDAN-HT. This method addresses the potential impact of nonlinear factors on phase extraction accuracy, consequently on ranging precision in the homodyne interference of the dual-grating. Building upon the ICEEMDAN algorithm, the signal undergoes iterative decomposition and reconstruction using the sample entropy criterion. The intrinsic mode functions (IMFs) obtained from multiple iterations are then reconstructed to obtain the complete signal. Through a simulation and comparison with other signal decomposition methods, the repeatability and completeness of signal reconstruction by Multiple ICEEMDAN are verified. Finally, an actual dual-grating ranging system is utilized to calibrate the spacing of the planar grating. Experimental results demonstrate that the calibration relative error of the Multiple ICEEMDAN-HT phase unwrapping method can be reduced to as low as 0.07%, effectively enhancing the signal robustness and spacing calibration precision.
Full article
(This article belongs to the Special Issue Novel Ultraviolet Laser: Generation, Properties and Applications)
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Open AccessReview
Synergy between AI and Optical Metasurfaces: A Critical Overview of Recent Advances
by
Zoran Jakšić
Photonics 2024, 11(5), 442; https://doi.org/10.3390/photonics11050442 - 9 May 2024
Abstract
The interplay between two paradigms, artificial intelligence (AI) and optical metasurfaces, nowadays appears obvious and unavoidable. AI is permeating literally all facets of human activity, from science and arts to everyday life. On the other hand, optical metasurfaces offer diverse and sophisticated multifunctionalities,
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The interplay between two paradigms, artificial intelligence (AI) and optical metasurfaces, nowadays appears obvious and unavoidable. AI is permeating literally all facets of human activity, from science and arts to everyday life. On the other hand, optical metasurfaces offer diverse and sophisticated multifunctionalities, many of which appeared impossible only a short time ago. The use of AI for optimization is a general approach that has become ubiquitous. However, here we are witnessing a two-way process—AI is improving metasurfaces but some metasurfaces are also improving AI. AI helps design, analyze and utilize metasurfaces, while metasurfaces ensure the creation of all-optical AI chips. This ensures positive feedback where each of the two enhances the other one: this may well be a revolution in the making. A vast number of publications already cover either the first or the second direction; only a modest number includes both. This is an attempt to make a reader-friendly critical overview of this emerging synergy. It first succinctly reviews the research trends, stressing the most recent findings. Then, it considers possible future developments and challenges. The author hopes that this broad interdisciplinary overview will be useful both to dedicated experts and a general scholarly audience.
Full article
(This article belongs to the Special Issue Recent Advances in Diffractive Optics)
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Open AccessArticle
Surface Plasmon Waveguide Based on Nested Dielectric Parallel Nanowire Pairs Coated with Graphene
by
Lixia Yu, Ji Liu and Wenrui Xue
Photonics 2024, 11(5), 441; https://doi.org/10.3390/photonics11050441 - 9 May 2024
Abstract
A kind of surface plasmon waveguide composed of two nested cylindrical dielectric parallel nanowire pairs coated with graphene was designed and studied. The dependence of the mode characteristics and the normalized gradient force of the lowest two modes supported by the waveguide on
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A kind of surface plasmon waveguide composed of two nested cylindrical dielectric parallel nanowire pairs coated with graphene was designed and studied. The dependence of the mode characteristics and the normalized gradient force of the lowest two modes supported by the waveguide on the parameters involved were analyzed by using the multipole method. To ensure rigor, the finite element method was employed to verify the accuracy of the multipole method, thus confirming its results. The results show that the multipole method is a powerful tool for handling this type of waveguide. The real part of the effective refractive index, the propagation length, the figure of merit, and the normalized gradient force can be significantly affected by the operating wavelength, the Fermi energy of graphene, the waveguide geometric parameters, and the refractive index of the inner dielectric nanowire. Due to the employment of nested dielectric nanowire pairs coated with graphene, this waveguide structure exhibits significant gradient force that surpasses 100 nN·μm−1·mW−1. The observed phenomena can be attributed to the interaction of the field with graphene. This waveguide holds promising potential for applications in micro/nano integration, optical tweezers, and sensing technologies.
Full article
(This article belongs to the Special Issue Design and Applications of Novel Nanophotonics Devices)
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Open AccessReview
On-Chip Supercontinuum Generation Pumped by Short Wavelength Fiber Lasers
by
Peng Chen, Zhe Long, Qi Cheng, Maozhuang Song, Wei Wang, Ruixue Liu, Zheng Zhang, Kai Xia, Zhen Yang, Lei Qian, Shengchuang Bai, Xunsi Wang, Peilong Yang, Peipeng Xu, El Sayed Yousef and Rongping Wang
Photonics 2024, 11(5), 440; https://doi.org/10.3390/photonics11050440 - 9 May 2024
Abstract
Supercontinuum (SC) generation pumped by fiber lasers with short wavelengths below 2.0 μm is important since it can provide a compact light source for various applications. We review the progress of SC generation in various materials regarding the formation of the waveguides and
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Supercontinuum (SC) generation pumped by fiber lasers with short wavelengths below 2.0 μm is important since it can provide a compact light source for various applications. We review the progress of SC generation in various materials regarding the formation of the waveguides and point out the existing issues in the current investigations and possible solutions in the future.
Full article
(This article belongs to the Special Issue High-Power Infrared Laser Systems: Design, Characterization, and Applications)
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Open AccessArticle
Wavelength-Tunable Chirped Pulse Amplification System (1720 nm–1800 nm) Based on Thulium-Doped Fiber
by
Xinyang Liu and Regina Gumenyuk
Photonics 2024, 11(5), 439; https://doi.org/10.3390/photonics11050439 - 8 May 2024
Abstract
Chirped pulse amplification (CPA) has been a commonly used methodology to obtain powerful ultrashort laser pulses ever since its first demonstration. However, wavelength-tunable CPA systems are much less common. Wavelength-tunable ultrashort and intense laser pulses are desirable in various fields such as nonlinear
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Chirped pulse amplification (CPA) has been a commonly used methodology to obtain powerful ultrashort laser pulses ever since its first demonstration. However, wavelength-tunable CPA systems are much less common. Wavelength-tunable ultrashort and intense laser pulses are desirable in various fields such as nonlinear spectroscopy and optical parametric amplification. In this work, we report a 1720 nm–1800 nm tunable CPA system based on Tm-doped fiber. The tunable CPA system contains a seed laser, a pulse stretcher, two cascaded amplifiers and a pulse compressor. The dispersion-managed seed laser cavity emits wavelength-tunable laser pulses with pulse durations of several ps and spectral widths from 25 nm to 34 nm. After being stretched temporally to tens of ps, the laser pulses are then amplified in two-stage amplifiers and compressed in a Treacy-type compressor. At 1720 nm, the maximum average power of 126 mW is obtained with a pulse duration of 507 fs; at 1800 nm, the maximum average power of 264 mW is obtained with a pulse duration of 294 fs. The pulse repetition rates are around 22.7 MHz. We perform an analysis of the system design based on numerical simulations and go on to suggest further steps for improvement. To the best of our knowledge, this is the first demonstration of a tunable CPA system beyond 1.1 μm. Considering the specific wavelength range, this wavelength-tunable CPA system is highly desirable for biomedical imaging, sensing, and parametric amplifiers.
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(This article belongs to the Section Lasers, Light Sources and Sensors)
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Open AccessArticle
EUV Radiation in the Range of 10–20 nm from Liquid Spray Targets Containing O, Cl, Br and I Atoms under Pulsed Laser Excitation
by
Valerie E. Guseva, Andrey N. Nechay, Alexander A. Perekalov and Nicolay I. Chkhalo
Photonics 2024, 11(5), 438; https://doi.org/10.3390/photonics11050438 - 8 May 2024
Abstract
The article describes the results of an investigation to determine the values of radiation intensities emitted by O-, Cl-, Br-, and I-containing liquid spray targets in absolute units in the wavelength range 10–20 nm when excited by pulsed laser radiation. The conversion coefficients
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The article describes the results of an investigation to determine the values of radiation intensities emitted by O-, Cl-, Br-, and I-containing liquid spray targets in absolute units in the wavelength range 10–20 nm when excited by pulsed laser radiation. The conversion coefficients of laser radiation into the EUV radiation are given for some wavelengths. The authors’ specially designed pulse extrusion liquid supply system was used to form the liquid spray targets. An Nd:YAG laser with λ = 1064 nm, τ = 8.4 ns, and Epulse = 0.8 J was used to excite the targets. Spectral measurements were made using a grazing incidence grating spectrometer–monochromator. The absolute intensities of a number of emission lines were also measured using a Bragg spectrometer based on a Mo/Be multilayer X-ray mirror, calibrated by both sensitivity and wavelength. The high values of absolute intensities of the liquid targets in the extreme ultraviolet wavelength range were demonstrated.
Full article
(This article belongs to the Special Issue Advances and Applications of Solid State Lasers)
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Open AccessArticle
Conversion and Active Control between BIC and Absorber in Terahertz Metasurface
by
Zhou Xi and Zhencheng Chen
Photonics 2024, 11(5), 437; https://doi.org/10.3390/photonics11050437 - 8 May 2024
Abstract
A multifunctional switchable metamaterial device based on graphene, a gold layer, polyimide, vanadiµm dioxide (VO2), and the sapphire substrate is designed in this paper. The top layer consists of a gold wire, graphene, and two split-ring resonators with the same parameters.
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A multifunctional switchable metamaterial device based on graphene, a gold layer, polyimide, vanadiµm dioxide (VO2), and the sapphire substrate is designed in this paper. The top layer consists of a gold wire, graphene, and two split-ring resonators with the same parameters. By adjusting the Fermi level of graphene, the regulation of BIC and quasi-BIC is realized, and the conversion between BIC and absorber is realized by adjusting the conductivity of VO2. When the device is converted into a wave-absorbing device with single-band absorption characteristics, the Fermi level of graphene at this time is 0.001 eV, the absorption peak at 0.820 THz is higher than 99.5%, and when the Fermi level of regulated graphene is 1 eV, the absorption peak at 0.667 THz is also higher than 99.5%. The peak frequency of the device is 0.640 THz when it converts to quasi-BIC. To the best of our knowledge, this is the first time that the conversion and regulation of BIC and absorber have been achieved using these two phase change materials. Moreover, by adjusting the parameters of the metamaterial structure, the working efficiency and frequency of BIC and absorber can be dynamically adjusted. The electric field distribution and surface current of metamaterials are further studied, and the physical mechanism of effective absorption and BIC is discussed. These results show that the metamaterials proposed in this paper have many advantages, such as terahertz absorption, BIC, and active device control, and are of great significance for developing terahertz multifunctional devices.
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(This article belongs to the Section Optoelectronics and Optical Materials)
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