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
The Generation of Equal-Intensity and Multi-Focus Optical Vortices by a Composite Spiral Zone Plate
Photonics 2024, 11(5), 466; https://doi.org/10.3390/photonics11050466 - 15 May 2024
Abstract
We propose a new vortex lens for producing multiple focused coaxial vortices with approximately equal intensities along the optical axis, termed equal-intensity multi-focus composite spiral zone plates (EMCSZPs). In this typical methodology, two concentric conventional spiral zone plates (SZPs) of different focal lengths
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We propose a new vortex lens for producing multiple focused coaxial vortices with approximately equal intensities along the optical axis, termed equal-intensity multi-focus composite spiral zone plates (EMCSZPs). In this typical methodology, two concentric conventional spiral zone plates (SZPs) of different focal lengths were composited together and the alternate transparent and opaque zones were arranged with specific m-bonacci sequence. Based on the Fresnel–Kirchhoff diffraction theory, the focusing properties of the EMCSZPs were calculated in detail and the corresponding demonstration experiment was been carried out to verify our proposal. The investigations indicate that the EMCSZPs indeed exhibit superior performance, which accords well with our physical design. In addition, the topological charges (TCs) of the multi-focus vortices can be flexibly selected and controlled by optimizing the parameters of the zone plates. These findings which were demonstrated by the performed experiment may open new avenues towards improving the performance of biomedical imaging, quantum computation and optical manipulation.
Full article
(This article belongs to the Special Issue Space Division Multiplexing Techniques)
Open AccessArticle
Simulation of a Pulsed Metastable Helium Lidar
by
Jiaxin Lan, Yuli Han, Ruocan Zhao, Tingdi Chen, Xianghui Xue, Dongsong Sun, Hang Zhou, Zhenwei Liu and Yingyu Liu
Photonics 2024, 11(5), 465; https://doi.org/10.3390/photonics11050465 - 15 May 2024
Abstract
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Measurements of atmosphere density in the upper thermosphere and exosphere are of great significance for studying space–atmosphere interactions. However, the region from 200 km to 1000 km has been a blind area for traditional ground-based active remote sensing techniques due to the limitation
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Measurements of atmosphere density in the upper thermosphere and exosphere are of great significance for studying space–atmosphere interactions. However, the region from 200 km to 1000 km has been a blind area for traditional ground-based active remote sensing techniques due to the limitation of facilities and the paucity of neutral atmosphere. To fulfill this gap, the University of Science and Technology of China is developing a powerful metastable helium resonance fluorescent lidar incorporating a 2 m aperture telescope, a high-energy 1083 nm pulsed laser, as well as a superconducting nanowire single-photon detector (SNSPD) with high quantum efficiency and low dark noise. The system is described in detail in this work. To evaluate the performance of the lidar system, numerical simulation is implemented. The results show that metastable helium density measurements can be achieved with a relative error of less than 20% above 370 km in winter and less than 200% in 270–460 km in summer, demonstrating the feasibility of metastable helium lidar.
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Open AccessArticle
The Generation of Circularly Polarized Isolated Attosecond Pulses with Tunable Helicity from CO Molecules in Polarization Gating Laser Fields
by
Shiju Chen, Hua Yuan, Feng Wang, Jiahang Song, Yue Zhao, Chunhui Yang, Tianxin Ou, Ru Zhang, Qiang Chang and Yuping Sun
Photonics 2024, 11(5), 464; https://doi.org/10.3390/photonics11050464 - 15 May 2024
Abstract
We theoretically demonstrate a scheme to generate circularly polarized (CP) isolated attosecond pulses (IAPs) with tunable helicity using a polarization gating laser field interacting with the CO molecule. The results show that a broadband CP supercontinuum is produced from the oriented CO molecule,
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We theoretically demonstrate a scheme to generate circularly polarized (CP) isolated attosecond pulses (IAPs) with tunable helicity using a polarization gating laser field interacting with the CO molecule. The results show that a broadband CP supercontinuum is produced from the oriented CO molecule, which supports the generation of an IAP with an ellipticity of 0.98 and a duration of 90 as. Furthermore, the helicity of the generated harmonics and IAP can be effectively controlled by modulating the laser field and the orientation angle of the CO molecule. Our method will advance research on chiral-specific dynamics and magnetic circular dichroism on the attosecond timescale.
Full article
(This article belongs to the Topic Recent Advances in Nonlinear Optics and Nonlinear Optical Materials)
Open AccessArticle
Generation of Propagation-Dependent OAM Self-Torque with Chirped Spiral Gratings
by
Ruediger Grunwald, Mathias Jurke, Max Liebmann, Alexander Treffer and Martin Bock
Photonics 2024, 11(5), 463; https://doi.org/10.3390/photonics11050463 - 15 May 2024
Abstract
The application of non-uniform spiral gratings to control the structure, topological parameters and propagation of orbital angular momentum (OAM) beams was studied experimentally with coherent near-infrared light. Adapted digital spiral grating structures were programmed into the phase map of a high-resolution liquid-crystal-on-silicon spatial
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The application of non-uniform spiral gratings to control the structure, topological parameters and propagation of orbital angular momentum (OAM) beams was studied experimentally with coherent near-infrared light. Adapted digital spiral grating structures were programmed into the phase map of a high-resolution liquid-crystal-on-silicon spatial light modulator (LCoS-SLM). It is shown that characteristic spatio-spectral anomalies related to Gouy phase shift can be used as pointers to quantify rotational beam properties. Depending on the sign and gradient of spatially variable periods of chirped spiral gratings (CSGs), variations in rotation angle and angular velocity were measured as a function of the propagation distance. Propagation-dependent self-torque is introduced in analogy to known local self-torque phenomena of OAM beams as obtained by the superposition of temporally chirped or phase-modulated wavepackets. Applications in metrology, nonlinear optics or particle trapping are conceivable.
Full article
(This article belongs to the Special Issue Structured Light Beams: Science and Applications)
Open AccessArticle
Characterizing Extreme Events in a Fabry–Perot Laser with Optical Feedback
by
Shanshan Ge, Yu Huang, Kun Li, Pei Zhou, Penghua Mu, Xin Zhu and Nianqiang Li
Photonics 2024, 11(5), 462; https://doi.org/10.3390/photonics11050462 - 15 May 2024
Abstract
The study of extreme events (EEs) in photonics has expanded significantly due to straightforward implementation conditions. EEs have not been discussed systematically, to the best of our knowledge, in the chaotic dynamics of a Fabry–Perot laser with optical feedback, so we address this
[...] Read more.
The study of extreme events (EEs) in photonics has expanded significantly due to straightforward implementation conditions. EEs have not been discussed systematically, to the best of our knowledge, in the chaotic dynamics of a Fabry–Perot laser with optical feedback, so we address this in the current contribution. Herein, we not only find EEs in all modes but also divide the EEs in total output into two categories for further discussion. The two types of EEs have similar statistical features to conventional rogue waves. The occurrence probability of EEs undergoes a saturation effect as the feedback strength increases. Additionally, we analyze the influence of feedback strength, feedback delay, and pump current on the probability of EEs defined by two criteria of EEs and find similar trends. We hope that this work contributes to a deep understanding and serves as inspiration for further research into various multimode semiconductor laser systems.
Full article
(This article belongs to the Special Issue Advanced Lasers and Their Applications II)
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Open AccessArticle
Integrated Analysis of Line-Of-Sight Stability of Off-Axis Three-Mirror Optical System
by
Yatao Lu, Bin Sun, Gui Mei, Qinglei Zhao, Zhongshan Wang, Yang Gao and Shuxin Wang
Photonics 2024, 11(5), 461; https://doi.org/10.3390/photonics11050461 - 15 May 2024
Abstract
As a space camera works in orbit, the stress rebound caused by gravity inevitably results in the deformation of its optomechanical structure, and the relative position change between different optical components will affect the Line-Of-Sight pointing of the camera. In this paper, the
[...] Read more.
As a space camera works in orbit, the stress rebound caused by gravity inevitably results in the deformation of its optomechanical structure, and the relative position change between different optical components will affect the Line-Of-Sight pointing of the camera. In this paper, the optical sensitivity calculation of a space camera’s Line-Of-Sight pointing is realized based on the optomechanical constraint equations, and the Line-Of-Sight equations are constructed using the second type of response (DRESP2) method to realize an optomechanical integrated analysis of the camera’s Line-Of-Sight stability at the structural finite element solver level. The verification results show that the Line-Of-Sight stability error is 6.38%, meaning that this method can identify the sensitive optical elements of the optical system efficiently and quickly. Thus, the method in this paper has important significance as a reference for the analysis of the Line-Of-Sight stability of complex optical systems.
Full article
(This article belongs to the Special Issue Recent Industrial Approaches of Optical Metasurfaces: Applications and Trends)
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Open AccessReview
Features of Adaptive Phase Correction of Optical Wave Distortions under Conditions of Intensity Fluctuations
by
Vladimir Lukin
Photonics 2024, 11(5), 460; https://doi.org/10.3390/photonics11050460 - 14 May 2024
Abstract
An analysis of the features of measurements and correction of phase distortions in optical waves propagating in the atmosphere at various levels of turbulence was performed. It is shown that with increasing intensity fluctuations, the limiting capabilities of phase correction decrease, and the
[...] Read more.
An analysis of the features of measurements and correction of phase distortions in optical waves propagating in the atmosphere at various levels of turbulence was performed. It is shown that with increasing intensity fluctuations, the limiting capabilities of phase correction decrease, and the phase of an optical wave that has passed through a turbulence layer consists of two components: potential and vortex. It was found that even in the region of weak fluctuations there is an overlap of spectral filtering functions for intensity and phase fluctuations. Areas of turbulence inhomogeneities have been identified that will have mutual influence and negatively affect the operation of the phase meter. It is noted that correlation functions, both phase and intensity, are less susceptible to this compared to structural functions. The results of experimental studies on the reconstruction of the wavefront of laser radiation distorted by atmospheric turbulence using a Shack–Hartmann wavefront sensor during vignetting and central screening of the entrance pupil in the optical system are presented. Studies have been carried out on the propagation of laser radiation along a horizontal atmospheric path for various levels of turbulence. The results are analyzed in terms of Zernike polynomials.
Full article
(This article belongs to the Special Issue Advances in Structured Light Generation and Manipulation)
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Open AccessArticle
Influence of the Experimental Setup on Electromagnetic Pulses in the VHF Band at Relativistic High-Power Laser Facilities
by
Michael Ehret, Luca Volpe, Jon Imanol Apiñaniz, Maria Dolores Rodríguez-Frías and Giancarlo Gatti
Photonics 2024, 11(5), 459; https://doi.org/10.3390/photonics11050459 - 14 May 2024
Abstract
We present experimental results for the controlled mitigation of the electromagnetic pulses (EMPs) produced in the interactions of a 1 PW high-power 30 fs Ti:Sa laser VEGA-3 with solid-density targets transparent to laser-forward-accelerated relativistic electrons. This study aims at the band of very
[...] Read more.
We present experimental results for the controlled mitigation of the electromagnetic pulses (EMPs) produced in the interactions of a 1 PW high-power 30 fs Ti:Sa laser VEGA-3 with solid-density targets transparent to laser-forward-accelerated relativistic electrons. This study aims at the band of very high frequencies (VHFs), i.e., those in the hundreds of MHz, which comprise the fundamental cavity modes of the rectangular VEGA-3 vacuum chamber. We demonstrate mode suppression by a tailoring of the laser-produced space charge distribution.
Full article
(This article belongs to the Special Issue Metrology at High-Power Laser Facilities: Primary and Secondary Laser-Driven Sources)
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Open AccessArticle
A 3D Reconstruction Method Based on Homogeneous De Bruijn-Encoded Structured Light
by
Weimin Li and Songlin Li
Photonics 2024, 11(5), 458; https://doi.org/10.3390/photonics11050458 - 14 May 2024
Abstract
Structured light three-dimensional reconstruction is one of the important methods for non-contact acquisition of sparse texture object surfaces. Variations in ambient illumination and disparities in object surface reflectance can significantly impact the fidelity of three-dimensional reconstruction, introducing considerable inaccuracies. We introduce a robust
[...] Read more.
Structured light three-dimensional reconstruction is one of the important methods for non-contact acquisition of sparse texture object surfaces. Variations in ambient illumination and disparities in object surface reflectance can significantly impact the fidelity of three-dimensional reconstruction, introducing considerable inaccuracies. We introduce a robust method for color speckle structured light encoding, which is based on a variant of the De Bruijn sequence, termed the Homogeneous De Bruijn Sequence. This innovative approach enhances the reliability and accuracy of structured light techniques for three-dimensional reconstruction by utilizing the distinctive characteristics of Homogeneous De Bruijn Sequences. Through a pruning process applied to the De Bruijn sequence, a structured light pattern with seven distinct color patches is generated. This approach ensures a more equitable distribution of speckle information.
Full article
(This article belongs to the Section Optical Interaction Science)
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Open AccessArticle
Mode Heterogeneous Multimode Power Splitter Based on Cascaded Mode-Dependent Splitters and Converters
by
Xin Xu, Hongliang Chen, Xin Fu and Lin Yang
Photonics 2024, 11(5), 457; https://doi.org/10.3390/photonics11050457 - 14 May 2024
Abstract
To the best of our knowledge, a novel concept of mode heterogeneity for the design of multimode devices is presented in this paper and applied to the design of scalable multimode power splitters. Based on a cascade of mode-dependent splitters and converters, we
[...] Read more.
To the best of our knowledge, a novel concept of mode heterogeneity for the design of multimode devices is presented in this paper and applied to the design of scalable multimode power splitters. Based on a cascade of mode-dependent splitters and converters, we achieve beam splitting and mode conversion for four modes from to in the bandwidth from 1525 nm to 1560 nm. The measurements of the device at 1550 nm show excellent performance, with the insertion loss ranging from 0.16 dB to 0.63 dB, crosstalk all below −16.71 dB, and power uniformity between 0.026 dB and 0.168 dB.
Full article
(This article belongs to the Special Issue Optical Communication, Sensing and Network)
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Open AccessArticle
Exploring the Origin of Lissajous Geometric Modes from the Ray Tracing Model
by
Xin-Liang Zheng, Yu-Han Fang, Wei-Che Chung, Cheng-Li Hsieh and Yung-Fu Chen
Photonics 2024, 11(5), 456; https://doi.org/10.3390/photonics11050456 - 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
[...] Read more.
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 - 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
[...] Read more.
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 - 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
[...] Read more.
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)
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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 - 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
[...] Read more.
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 - 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,
[...] Read more.
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)
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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 - 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+
[...] Read more.
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 - 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
[...] Read more.
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 - 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
[...] Read more.
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 - 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
[...] Read more.
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)
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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 - 10 May 2024
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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
[...] Read more.
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.
Full article
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Emerging Terahertz Technologies for Integrated Sensing and Communication
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Applied Sciences, Electronics, Optics, Photonics, Technologies
The Extended Technological Platform Based on Optics and Microwaves: Conventional and Hybrid Solutions
Topic Editors: Francesco Prudenzano, Antonella D’Orazio, Maurizio FerrariDeadline: 30 September 2024
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Advances in Infrared Spectroscopy and Raman Spectroscopy
Guest Editors: Zehua Han, Yujie ShenDeadline: 20 May 2024
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Optical Technologies Supporting 5G/6G Mobile Networks
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Micro-Nano Optical Devices
Guest Editors: Yan Shen, Yanfeng ZhangDeadline: 15 June 2024
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Editorial Board Members’ Collection Series: Photonics Sensors
Guest Editors: Carlos Marques, Flavio EspositoDeadline: 30 June 2024