Next Issue
Volume 12, September
Previous Issue
Volume 12, July
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
3.5
1.9
Journals
Photonics
Volume 12
Issue 8
share announcement

Photonics, Volume 12, Issue 8 (August 2025) – 92 articles

Cover Story (view full-size image): To beat the heat and inefficiency that limit microchip lasers, we bonded Nd:YAG/Cr4+:YAG and pumped it through a fiber splitter. At 4.02 mJ, 100 Hz, four linear beams emerge, each 0.964 mJ, giving 23.98% optical conversion. Energy shares: 22.61%, 24.46%, 25.50%, and 27.43%; pulse widths: 2.18–2.21 ns. The far field evolves from one circle to four spots; the lower-right beam yields Mx2 = 1.181 and My2 = 1.289. Simulations at 293 K show that split pumping cuts Nd:YAG volume ΔT by 28.8%, peak ΔT by 66%, and swing by 78%. Compact, low-cost, and high-damage, it suits car ignition, LiDAR, and LIBS. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
12 pages, 3310 KB  
Article
Resolution Enhancement in Extreme Ultraviolet Ptychography Using a Refined Illumination Probe and Small-Etendue Source
by Seungchan Moon, Junho Hong, Taeho Lee and Jinho Ahn
Photonics 2025, 12(8), 831; https://doi.org/10.3390/photonics12080831 - 21 Aug 2025
Viewed by 370
Abstract
Extreme ultraviolet (EUV) ptychography is a promising actinic mask metrology technique capable of providing aberration-free images with subwavelength resolution. However, its performance is fundamentally constrained by the strong absorption of EUV light and the limited detection of high-frequency diffraction signals, which are critical [...] Read more.
Extreme ultraviolet (EUV) ptychography is a promising actinic mask metrology technique capable of providing aberration-free images with subwavelength resolution. However, its performance is fundamentally constrained by the strong absorption of EUV light and the limited detection of high-frequency diffraction signals, which are critical for resolving fine structural details. In this study, we demonstrate significant improvements in EUV ptychographic imaging by implementing an upgraded EUV source system with reduced source etendue and applying an illumination aperture to spatially refine the probe. This approach effectively enhances the photon flux and spatial coherence, resulting in an increased signal-to-noise ratio of the high-frequency diffraction components and an extended maximum detected spatial frequency. Simulations and experimental measurements using a Siemens star pattern confirmed that the refined probe enabled more robust phase retrieval and higher-resolution image reconstruction. Consequently, we achieved a half-pitch resolution of 46 nm, corresponding to a critical dimension of 11.5 nm at the wafer plane. These findings demonstrate the enhanced capability of EUV ptychography as a high-fidelity actinic metrology tool for next-generation EUV mask characterization. Full article
(This article belongs to the Special Issue Computational Imaging for Semiconductor Devices Metrology Applications)
►▼ Show Figures

Figure 1

9 pages, 1887 KB  
Article
Tunable High-Power 420 nm Laser with External Cavity Frequency Doubling: Toward Efficient Rubidium Rydberg Excitation
by Zhongxiao Xu, Xin Jia, Keyu Qin, Weisen Wang, Yaoting Zhou and Donghao Li
Photonics 2025, 12(8), 830; https://doi.org/10.3390/photonics12080830 - 21 Aug 2025
Viewed by 395
Abstract
The external cavity frequency doubling technique serves as a potent method for generating short-wavelength lasers, yet achieving high-power outputs remains challenging due to the thermal lens effect. This study systematically investigates the generation mechanism of the thermal lens effect and its impact on [...] Read more.
The external cavity frequency doubling technique serves as a potent method for generating short-wavelength lasers, yet achieving high-power outputs remains challenging due to the thermal lens effect. This study systematically investigates the generation mechanism of the thermal lens effect and its impact on laser performance. By optimizing the bow-tie cavity design and leveraging a large beam waist of 106 µm to suppress thermal-induced distortions, we demonstrate a tunable 420 nm laser with up to 800 mW of output power and a peak conversion efficiency of 77%. The fundamental light source, a Ti:Sa laser locked to an ultra-stable cavity, ensures a narrow linewidth, flexible tunability, and long-term frequency stability. This high-performance blue laser enables the efficient Rydberg excitation of rubidium atoms, presenting critical applications in quantum computing, quantum simulation, and quantum precision measurement. Full article
►▼ Show Figures

Figure 1

25 pages, 3282 KB  
Review
Linear-Mode Gain HgCdTe Avalanche Photodiodes for Weak-Target Spaceborne Photonic System
by Hui Yu, Zhichao Zhang, Ming Liu, Weirong Xing, Qing Wu, Yi Zhang, Weiting Zhang, Jialin Xu and Qiguang Tan
Photonics 2025, 12(8), 829; https://doi.org/10.3390/photonics12080829 - 20 Aug 2025
Viewed by 503
Abstract
Spectroscopic observations of Earth-like exoplanets and ultra-faint galaxies–top scientific priorities for the coming decades–involve measuring broadband signals at rates of only a few photons per square meter per hour. This imposes exceptional requirements on the detector performance, necessitating dark currents below 1 e [...] Read more.
Spectroscopic observations of Earth-like exoplanets and ultra-faint galaxies–top scientific priorities for the coming decades–involve measuring broadband signals at rates of only a few photons per square meter per hour. This imposes exceptional requirements on the detector performance, necessitating dark currents below 1 e−/pixel/kilo second, read noise under 1 e−/pixel/frame, and the ability to handle large-format arrays–capabilities that are not yet met by most existing infrared detectors. In addition, spaceborne LiDAR systems require photodetectors with exceptional sensitivity, compact size, low power consumption, and multi-channel capability to facilitate long-range range finding, topographic mapping, and active spectroscopy without increasing the instrument burden. MCT Avalanche photodiodes arrays offer high internal gain, pixelation, and photon-counting performance across SW to MW wavelengths needed for multi-beam and multi-wavelength measurements, marking them as a critical enabling technology for next-generation planetary and Earth science LiDAR missions. This work reports the latest progress in developing Hg1−xCdxTe linear-mode e-APDs at premier industrial research institutions, including relevant experimental data, simulations and major project planning. Related studies are summarized to demonstrate the practical and iterative approach for device fabrication, which have a transformative impact on the evolution of this discipline. Full article
(This article belongs to the Special Issue Emerging Trends in Photodetector Technologies)
►▼ Show Figures

Figure 1

18 pages, 3063 KB  
Article
Diffuse Correlation Blood Flow Tomography Based on Conv-TransNet Model
by Xiaojuan Zhang, Wen Yan, Peng Zhang, Xiaogang Tong, Haifeng Zhou and Yu Shang
Photonics 2025, 12(8), 828; https://doi.org/10.3390/photonics12080828 - 20 Aug 2025
Viewed by 389
Abstract
Diffuse correlation tomography (DCT) is an emerging technique for detecting diseases associated with localized abnormal perfusion from near-infrared light intensity temporal autocorrelation functions (g2(τ)). However, a critical drawback of traditional reconstruction methods is the imbalance between optical measurements [...] Read more.
Diffuse correlation tomography (DCT) is an emerging technique for detecting diseases associated with localized abnormal perfusion from near-infrared light intensity temporal autocorrelation functions (g2(τ)). However, a critical drawback of traditional reconstruction methods is the imbalance between optical measurements and the voxels to be reconstructed. To address this issue, this paper proposes Conv-TransNet, a convolutional neural network (CNN)–Transformer hybrid model that directly maps g2(τ) data to blood flow index (BFI) images. For model training and testing, we constructed a dataset of 18,000 pairs of noise-free and noisy g2(τ) data with their corresponding BFI images. In simulation validation, the root mean squared error (RMSE) for the five types of anomalies with noisy data are 2.13%, 4.43%, 2.15%, 4.05%, and 4.39%, respectively. The MJR (misjudgment ratio)of them are close to zero. In the phantom experiments, the CONTRAST of the quasi-solid cross-shaped anomaly reached 0.59, with an MJR of 2.21%. Compared with the traditional Nth-order linearization (NL) algorithm, the average CONTRAST of the speed-varied liquid tubular anomaly increased by 0.55. These metrics also demonstrate the superior performance of our method over traditional CNN-based approaches. The experimental results indicate that the Conv-TransNet model would achieve more accurate and robust reconstruction, suggesting its potential as an alternative for blood flow imaging. Full article
(This article belongs to the Section Biophotonics and Biomedical Optics)
►▼ Show Figures

Figure 1

19 pages, 1299 KB  
Article
Structured Emission and Entanglement Dynamics of a Giant Atom in a Photonic Creutz Ladder
by Vassilios Yannopapas
Photonics 2025, 12(8), 827; https://doi.org/10.3390/photonics12080827 - 20 Aug 2025
Viewed by 413
Abstract
We explore the spontaneous emission dynamics of a giant atom coupled to a photonic Creutz ladder, focusing on how flat-band frustration and synthetic gauge fields shape atom–photon interactions. The Creutz ladder exhibits perfectly flat bands, Aharonov–Bohm caging, and topological features arising from its [...] Read more.
We explore the spontaneous emission dynamics of a giant atom coupled to a photonic Creutz ladder, focusing on how flat-band frustration and synthetic gauge fields shape atom–photon interactions. The Creutz ladder exhibits perfectly flat bands, Aharonov–Bohm caging, and topological features arising from its nontrivial hopping structure. By embedding the giant atom at multiple spatially separated sites, we reveal interference-driven emission control and the formation of nonradiative bound states. Using both spectral and time-domain analyses, we uncover strong non-Markovian dynamics characterized by persistent oscillations, long-lived entanglement, and recoherence cycles. The emergence of bound-state poles in the spectral function is accompanied by spatially localized photonic profiles and directionally asymmetric emission, even in the absence of band dispersion. Calculations of von Neumann entropy and atomic purity confirm the formation of coherence-preserving dressed states in the flat-band regime. Furthermore, the spacetime structure of the emitted field displays robust zig-zag interference patterns and synthetic chirality, underscoring the role of geometry and topology in photon transport. Our results demonstrate how flat-band photonic lattices can be leveraged to engineer tunable atom–photon entanglement, suppress radiative losses, and create structured decoherence-free subspaces for quantum information applications. Full article
(This article belongs to the Special Issue Recent Progress in Optical Quantum Information and Communication)
►▼ Show Figures

Figure 1

13 pages, 690 KB  
Article
Design and Optimization of Polarization-Maintaining Low-Loss Hollow-Core Anti-Resonant Fibers Based on a Multi-Objective Genetic Algorithm
by Zhiling Li, Yingwei Qin, Jingjing Ren, Xiaodong Huang and Yanan Bao
Photonics 2025, 12(8), 826; https://doi.org/10.3390/photonics12080826 - 20 Aug 2025
Viewed by 418
Abstract
In this work, a novel polarization-maintaining hollow-core fiber structure featuring a semi-circular nested dual-ring geometry is proposed. To simultaneously optimize two inherently conflicting performance metrics, namely, birefringence and confinement loss, a multi objective genetic algorithm is employed for geometric parameter tuning, resulting in [...] Read more.
In this work, a novel polarization-maintaining hollow-core fiber structure featuring a semi-circular nested dual-ring geometry is proposed. To simultaneously optimize two inherently conflicting performance metrics, namely, birefringence and confinement loss, a multi objective genetic algorithm is employed for geometric parameter tuning, resulting in a set of Pareto-optimal solutions. At the target wavelength of 1550 nm, the first optimal design achieves birefringence exceeding 1×10−4 over a 1275 nm bandwidth while maintaining confinement loss around 100 dB/m; the second design maintains birefringence above 1×10−4 across a 1000 nm spectral range, with confinement loss on the order of 10−1 dB/m. These optimized designs offer a promising approach for improving the performance of polarization-sensitive applications such as interferometric sensing and high coherence laser systems. The results confirm the suitability of multi-objective genetic algorithms for integrated multi-objective fiber optimization and provide a new strategy for designing low-loss and high-birefringence fiber devices. Full article
►▼ Show Figures

Figure 1

14 pages, 4281 KB  
Article
Joint Rx IQ Imbalance Compensation and Timing Recovery for Faster-than-Nyquist WDM Systems
by Jialin You
Photonics 2025, 12(8), 825; https://doi.org/10.3390/photonics12080825 - 19 Aug 2025
Viewed by 307
Abstract
Faster-than-Nyquist (FTN) tight filtering introduces serious inter-symbol interference (ISI) impairment, leading to an insufficient compensation range for conventional IQ imbalance compensation algorithms. Furthermore, receiver (Rx) IQ imbalance and ISI impairments significantly increase the convergence cost required by the squared Gardner phase detector (SGPD) [...] Read more.
Faster-than-Nyquist (FTN) tight filtering introduces serious inter-symbol interference (ISI) impairment, leading to an insufficient compensation range for conventional IQ imbalance compensation algorithms. Furthermore, receiver (Rx) IQ imbalance and ISI impairments significantly increase the convergence cost required by the squared Gardner phase detector (SGPD) timing recovery algorithm to establish a timing synchronization loop. This paper proposes a joint Rx IQ compensation and timing recovery scheme. By embedding a two-stage IQ imbalance compensation algorithm into the timing recovery feedback loop, the proposed scheme could effectively estimate and compensate for Rx IQ imbalance. Meanwhile, thanks to the innovative scheme, which equalizes Rx IQ imbalance and ISI during the timing feedback loop, the convergence cost of timing recovery could be reduced compared with the conventional blind frequency domain (BFD) scheme. The simulation results of 128 GBaud polarization multiplexing (PM) 16-quadrature amplitude modulation (QAM) FTN wavelength division multiplexing (WDM) transmission systems demonstrate that the proposed scheme could bring about 14%, 12.5%, and 16.6% improvements in the compensation range for Rx IQ amplitude imbalance, phase imbalance, and skew, respectively, compared with the conventional one. Meanwhile, the convergence cost is reduced by at least 31% with a 0.9 acceleration factor. In addition, 40 GBaud PM-16QAM FTN experiment results show that the proposed scheme could bring about a 0.8 dB improvement in the optical signal noise ratio (OSNR) compared with the conventional BFD scheme. Full article
(This article belongs to the Special Issue Optical Communication Networks: Challenges and Opportunities)
►▼ Show Figures

Figure 1

10 pages, 1397 KB  
Article
Encoding and Verification of Composite Vortex Beams with Spaced Orbital Angular Momentum
by Tianpeng Xu, Xinping Han, Xiaodie Wang, Sichen Lei, Pengfei Wu and Huiqin Wang
Photonics 2025, 12(8), 824; https://doi.org/10.3390/photonics12080824 - 19 Aug 2025
Viewed by 409
Abstract
A novel encoding method based on the orbital angular momentum (OAM) mode and radial mode of composite vortex beams is proposed. The superposition of two vortex beams generates 32 different types of composite vortex beams: one of them is a Laguerre–Gaussian (LG) beam [...] Read more.
A novel encoding method based on the orbital angular momentum (OAM) mode and radial mode of composite vortex beams is proposed. The superposition of two vortex beams generates 32 different types of composite vortex beams: one of them is a Laguerre–Gaussian (LG) beam with a fixed OAM mode and radial mode, and the other is a LG beam containing four radial modes (p = 0, 1, 2, 3) and eight OAM modes with the same interval (l = ±3, ±5, ±7, ±9). A specially designed composite fork-shaped grating (CFG) is utilized to generate the intensity array pattern, and the received composite vortex beam is diffracted into a Gaussian beam with the relevant coordinates. Based on the coordinates and the number of bright rings in the intensity pattern, the OAM modes and radial modes of the two vortex beams composing the superposition state are determined, and finally the received composite vortex beam is decoded into the initially propagated information sequence. The correctness and effectiveness of the proposed encoding are confirmed through the comparative analysis of the correlation of the optical fields at both the transmitter and receiver in the two scenarios of interval and non-interval encoding. The proposed encoding method can significantly improve the efficiency of information transmission and its resistance to interference, holding great potential for future applications in free-space optical communication. Full article
►▼ Show Figures

Figure 1

22 pages, 9617 KB  
Article
An Improved PCA and Jacobian-Enhanced Whale Optimization Collaborative Method for Point Cloud Registration
by Haiman Chu, Jingjing Fan, Zai Luo, Yinbao Cheng, Yingqi Tang and Yaru Li
Photonics 2025, 12(8), 823; https://doi.org/10.3390/photonics12080823 - 19 Aug 2025
Viewed by 236
Abstract
Scanned data often contain substantial outliers due to environmental interference, which drastically decreases the performance of traditional registration algorithms. To address this issue, this article proposes an improved principal component analysis (PCA) and Jacobian-enhanced whale optimization collaborative method for point cloud registration. First, [...] Read more.
Scanned data often contain substantial outliers due to environmental interference, which drastically decreases the performance of traditional registration algorithms. To address this issue, this article proposes an improved principal component analysis (PCA) and Jacobian-enhanced whale optimization collaborative method for point cloud registration. First, an improved PCA point cloud initial registration algorithm is proposed by introducing the normal vector local information to set the screening conditions. This algorithm can streamline the original set of 48 candidate rotation matrices down to 4, achieving rapid point cloud registration at the data level between the scanned and model point clouds. Second, a Jacobian whale optimization algorithm for fine registration (JWOA-FR) is proposed by incorporating local gradient information. The algorithm employs gradient descent on optimal whale individuals to dynamically guide global search updates, thereby enhancing both registration accuracy and efficiency. Finally, a threshold is set to remove the outliers contained in the workpieces based on the information of the matched point pairs. The iterative closest point (ICP) algorithm is further used to improve registration accuracy for data without outliers. The experimental results showed that registration errors of large workpieces 1, 2, and 3 were 2.0755 mm, 2.3955 mm, and 2.5823 mm, respectively, after outlier removal, which indicates that the proposed method is applicable to data with outliers, and the registration accuracy meets the requirements. Full article
(This article belongs to the Special Issue Advancements in Optics and Laser Measurement)
►▼ Show Figures

Figure 1

9 pages, 807 KB  
Communication
Optimization of the Saturable Absorption of 2D Bi2Te3 Layers
by Nayla Jimenez de la Vega, Arjun Karimbana Kandy, Fabien Lemarchand, Andrea Campos, Martiane Cabié, Carine Perrin-Pellegrino, Julien Lumeau, Jean-Yves Natoli and Konstantinos Iliopoulos
Photonics 2025, 12(8), 822; https://doi.org/10.3390/photonics12080822 - 19 Aug 2025
Viewed by 301
Abstract
The saturable absorption of 2D Bi2Te3 layers is studied by using the Z-scan technique employing infrared 400 fs laser pulses. Optimization of the nonlinearities has been carried out by measuring the third-order nonlinear susceptibilities as a function of the film [...] Read more.
The saturable absorption of 2D Bi2Te3 layers is studied by using the Z-scan technique employing infrared 400 fs laser pulses. Optimization of the nonlinearities has been carried out by measuring the third-order nonlinear susceptibilities as a function of the film thickness. A thorough optimization of the thin film annealing conditions has been performed and is presented. For each thickness, the annealing parameters have been separately investigated. Scanning electron microscopy, X-ray diffraction, and UV-Vis spectrophotometry studies have also been performed on the as-deposited and crystallized 2D layers. Full article
►▼ Show Figures

Figure 1

33 pages, 17720 KB  
Review
Photonic Integrated Circuits: Research Advances and Challenges in Interconnection and Packaging Technologies
by Wenchao Tian, Yifan Wang, Haojie Dang, Huahua Hou and Yuanyuan Xi
Photonics 2025, 12(8), 821; https://doi.org/10.3390/photonics12080821 - 18 Aug 2025
Viewed by 948
Abstract
Silicon photonics, serving as a cornerstone technology in modern information technology, demonstrates significant application potential in critical scenarios such as high-speed data center interconnects and integrated optical communication systems. Facing the persistent demand for information processing capabilities in the post-Moore era, photonic chips [...] Read more.
Silicon photonics, serving as a cornerstone technology in modern information technology, demonstrates significant application potential in critical scenarios such as high-speed data center interconnects and integrated optical communication systems. Facing the persistent demand for information processing capabilities in the post-Moore era, photonic chips have emerged as a pivotal direction for overcoming the performance bottlenecks of traditional chips, leveraging their advantages of low power consumption, high speed, and high integration density. This review focuses specifically on the optical interconnection and packaging technologies for photonic chips. It comprehensively analyzes the research frontiers and key challenges in packaging technologies, encompassing efficient fiber-to-chip coupling techniques, chip-scale optical interconnection technologies, and 2D, 2.5D, and 3D stacked co-packaged optics technologies. By synthesizing and summarizing recent research advances, this paper aims to provide researchers in related fields with a systematic understanding of photonic integrated circuit technology. Furthermore, it seeks to offer insights for future technological breakthroughs in device optimization, packaging innovation, and system-level applications of photonic integrated circuits. Full article
(This article belongs to the Special Issue Photonic Integrated Circuits: Recent Advances and Future Perspectives)
►▼ Show Figures

Figure 1

49 pages, 5199 KB  
Review
Recent Advances in C-Band High-Power and High-Speed Radio Frequency Photodiodes: Review, Theory and Applications
by Saeed Haydhah, Fabien Ferrero, Xiupu Zhang and Ahmed A. Kishk
Photonics 2025, 12(8), 820; https://doi.org/10.3390/photonics12080820 - 17 Aug 2025
Viewed by 431
Abstract
A review of the recent research work on high-power and high-speed (HPHS) Ge-on-Si photodiode design is presented, using Silicon Photonics (SiPh) technology, suitable for Radio-over-Fiber base station schemes. The Photodiode (PD) principle of operation, its structure for high RF photogenerated power, and the [...] Read more.
A review of the recent research work on high-power and high-speed (HPHS) Ge-on-Si photodiode design is presented, using Silicon Photonics (SiPh) technology, suitable for Radio-over-Fiber base station schemes. The Photodiode (PD) principle of operation, its structure for high RF photogenerated power, and the achieved PD wide bandwidth are presented. Then, the PD equivalent circuit models are introduced to obtain the PD S-parameters and operating bandwidth, such that efficient power coupling to mmWave loads is realized. Then, the PD theoretical transit-time and RC-time bandwidths are presented, and the PD photocurrent behavior against input optical power, and the optical signal manipulation techniques to improve the PD performance are also presented. After that, the impedance matching techniques between the PD output impedance and antenna input impedance are presented. Finally, recent photonic mmWave antenna designs are introduced. Full article
►▼ Show Figures

Figure 1

27 pages, 4744 KB  
Review
Recent Progress in Liquid Crystal-Based Smart Windows with Low Driving Voltage and High Contrast
by Yitong Zhou and Guoqiang Li
Photonics 2025, 12(8), 819; https://doi.org/10.3390/photonics12080819 - 16 Aug 2025
Viewed by 590
Abstract
Smart windows based on liquid crystal (LC) have made significant advancements over the past decade. As critical mediators of outdoor light entering indoor spaces, these windows can dynamically and rapidly adjust their transmittance to adapt to changing environmental conditions, thereby enhancing living comfort. [...] Read more.
Smart windows based on liquid crystal (LC) have made significant advancements over the past decade. As critical mediators of outdoor light entering indoor spaces, these windows can dynamically and rapidly adjust their transmittance to adapt to changing environmental conditions, thereby enhancing living comfort. To further improve device performance, reduce energy consumption, and ensure greater safety for everyday use, scientists have recently focused on reducing driving voltage and enhancing contrast ratio, achieving notable progress in these areas. This article provides a concise overview of the fundamental principles and major applications of LC smart windows. It systematically reviews recent advancements over the past two years in improving these two key optical properties for variable transmittance LC smart windows, both internally and externally, and highlights the remaining challenges alongside potential future directions for development. Full article
(This article belongs to the Section Optoelectronics and Optical Materials)
►▼ Show Figures

Figure 1

13 pages, 5414 KB  
Article
Modelling of Tiled Grating Arrangement Efficiency
by Haritha Vijayakumar Sheela, Gabor Horváth and Miklós Füle
Photonics 2025, 12(8), 818; https://doi.org/10.3390/photonics12080818 - 15 Aug 2025
Viewed by 301
Abstract
The precise alignment of individual diffraction grating units within a tiled grating assembly (TGA) is essential for enhancing the quality of optical throughput and overall functional performance of such kinds of optical systems. This study presents a comprehensive simulation analysis of TGAs comprising [...] Read more.
The precise alignment of individual diffraction grating units within a tiled grating assembly (TGA) is essential for enhancing the quality of optical throughput and overall functional performance of such kinds of optical systems. This study presents a comprehensive simulation analysis of TGAs comprising two and four gratings to assess the sensitivity of optical imaging performance to a range of induced alignment errors. The misalignments are systematically introduced to the grating sections in the tiled grating assemblies, and their effects in far-field imaging are examined and compared. The results highlight the critical role of accurate alignment in maintaining coherent beam combination and optimal system performance. Zemax OpticStudio®-based simulations offer valuable insights for designing high-performance, large-aperture grating systems and pave the way for future experimental validation and integration. Full article
►▼ Show Figures

Figure 1

21 pages, 2646 KB  
Article
Effects of Er:YAG and Nd:YAG Lasers with Photobiomodulation on Alveolar Bone Preservation Post-Extraction: A Randomized Clinical Control Trial
by Magdalena Gryka-Deszczyńska, Zuzanna Grzech-Leśniak, Diana Dembicka-Mączka, Rafał Wiench, Marzena Dominiak, Jacek Matys and Kinga Grzech-Leśniak
Photonics 2025, 12(8), 817; https://doi.org/10.3390/photonics12080817 - 15 Aug 2025
Viewed by 606
Abstract
(1) Background: This study aimed to compare alveolar bone preservation and early healing outcomes following a comprehensive laser-assisted post-extraction protocol compared to conventional extraction alone. In addition, the potential influence of serum vitamin D levels on bone regeneration was assessed. (2) Methods: Thirty [...] Read more.
(1) Background: This study aimed to compare alveolar bone preservation and early healing outcomes following a comprehensive laser-assisted post-extraction protocol compared to conventional extraction alone. In addition, the potential influence of serum vitamin D levels on bone regeneration was assessed. (2) Methods: Thirty tooth extractions were performed and randomized into two groups: a test group (G1, n =15) and a control group (G2, n = 15). G1 received a laser-assisted protocol using Er:YAG and Nd:YAG lasers for granulation tissue removal, socket disinfection, clot stabilization, de-epithelialization, and photobiomodulation (PBM) with the Genova handpiece (LightWalker, Fotona, Slovenia). G2 underwent standard mechanical extractions and socket debridement without laser. (3) Results: Procedures in G1 were on average 8.7 min longer, but patients in this group reported significantly lower postoperative pain during the first three days (p < 0.05). A statistically significant difference in alveolar height was observed at the distal lingual site (25.4 mm vs. 21.7 mm; p = 0.046), with other sites showing a trend toward significance. Cumulative bone preservation, measured by Bone Loss Index (BLI4), was significantly better in the laser group. Notably, a positive correlation was found between serum vitamin D levels and bone preservation: each 1 ng/mL increase in vitamin D corresponded to a 0.18 mm gain in alveolar height (p = 0.021). (4) Conclusions: The comprehensive laser-assisted post-extraction protocol reduced postoperative pain and improved alveolar bone preservation, particularly at the lingual distal site. Serum vitamin D levels positively correlated with healing outcomes, suggesting a potential synergistic role of systemic and local regenerative factors. Full article
(This article belongs to the Special Issue Photonics: 10th Anniversary)
►▼ Show Figures

Figure 1

14 pages, 3027 KB  
Article
Generation of Four-Channel Multi-Polarization Bessel Vortex Beams with Equal Divergence Angle Based on Co-Aperture Metasurface
by Zhiwei Wang, Yongzhong Zhu, Jun Chen and Wenxuan Xie
Photonics 2025, 12(8), 816; https://doi.org/10.3390/photonics12080816 - 15 Aug 2025
Viewed by 379
Abstract
This paper proposes a co-aperture reflective metasurface that successfully generates four-channel Bessel vortex beams with equal divergence angle in both Ka and Ku bands. Initially, a frequency-selective surface (FSS) is employed to suppress inter-unit crosstalk. Subsequently, modified cross-dipole metasurface units are implemented using [...] Read more.
This paper proposes a co-aperture reflective metasurface that successfully generates four-channel Bessel vortex beams with equal divergence angle in both Ka and Ku bands. Initially, a frequency-selective surface (FSS) is employed to suppress inter-unit crosstalk. Subsequently, modified cross-dipole metasurface units are implemented using spin-decoupling theory to achieve independent multi-polarization control. Through theoretical calculation-based divergence angle engineering, the dual-concentric-disk structure integrated with multi-polarization control demonstrates enhanced aperture utilization efficiency compared to conventional partitioning strategies, yielding high-purity equal-divergence-angle Bessel vortex beams across multiple modes. Finally, experiments on the metasurface fabricated via printed circuit board (PCB) technology verify that the design simultaneously generates x-polarization +1 mode and y-polarization +2 mode equal divergence angle Bessel vortex beams in the Ku band and ±3 mode beams in the Ka band. Vortex beam divergence angles remain stable at 9° ± 0.5° under diverse polarization states and modes, with modal purity reaching 65–80% at the main radiation direction. This work provides a straightforward implementation method for generating equal-divergence-angle vortex beams applicable to Orbital Angular Momentum (OAM) multimode multiplexing and vortex wave detection. Full article
►▼ Show Figures

Figure 1

15 pages, 3647 KB  
Article
3D Printed Galilean Telescope for Low-Vision Patients
by Daniel Aguirre-Aguirre, Itzel Muñoz-Juárez, Martin Isaías Rodríguez-Rodríguez, Brenda Villalobos-Mendoza, Ruth Eva Hernández-Carbajal, Rufino Díaz-Uribe and Rafael Izazaga-Pérez
Photonics 2025, 12(8), 815; https://doi.org/10.3390/photonics12080815 - 15 Aug 2025
Viewed by 389
Abstract
Low vision is a condition in which a person experiences a significant loss of visual acuity or visual field that ordinary glasses, surgery, or medication cannot correct. Individuals suffering from this condition struggle to perform daily tasks, even when using glasses or contact [...] Read more.
Low vision is a condition in which a person experiences a significant loss of visual acuity or visual field that ordinary glasses, surgery, or medication cannot correct. Individuals suffering from this condition struggle to perform daily tasks, even when using glasses or contact lenses. In some cases, telescopes are recommended for patients with low vision diagnosis because they could help them improve their quality of life. Therefore, we propose a 3D-printed Galilean telescope for low-vision patients, accessible to both the vulnerable and nonvulnerable sectors of the population, with the advantages that the fabrication time, cost, and weight are considerably reduced. The performance of the 3D-printed Galilean telescope was evaluated by comparing it to an identical N-BK7 glass Galilean telescope design, obtaining a difference of 0.49 lp/mm in optical resolution. Clinical results from a patient with low vision, obtained as part of a proof-of-concept study, showed that the 3D-printed Galilean telescope improved the patient’s visual acuity, increasing it by up to 4 lines on the LEA numbers, from 10/80 to 10/32. Additionally, the 3D telescope enhanced the patient’s contrast sensitivity, improving it from 6 cpd (cycles per degree) level 8 to 18 cpd level 4. Full article
(This article belongs to the Special Issue Advances in Visual Optics)
►▼ Show Figures

Figure 1

12 pages, 2969 KB  
Article
Switchable Single- and Dual-Wavelength Yb:YAG Laser Enabled by a Dual-Confocal Resonator
by Enhuai Liang, Zhiqi Zhou, Menghua Jiang, Wenbin Qin, Youqiang Liu, Yinhua Cao and Zhiyong Wang
Photonics 2025, 12(8), 814; https://doi.org/10.3390/photonics12080814 - 14 Aug 2025
Viewed by 306
Abstract
In this manuscript, we demonstrated a switchable single-/dual-wavelength Yb:YAG laser based on intracavity loss modulation in a dual-confocal resonator configuration. The laser employed a dual-confocal resonator with a length of 175 mm that enabled the controlled adjustment of geometric losses through precise angular [...] Read more.
In this manuscript, we demonstrated a switchable single-/dual-wavelength Yb:YAG laser based on intracavity loss modulation in a dual-confocal resonator configuration. The laser employed a dual-confocal resonator with a length of 175 mm that enabled the controlled adjustment of geometric losses through precise angular modulation of the output coupler, achieving stable switching between single- and dual-wavelength operations. Under a maximum pump power of 20.98 W, the laser delivered 1.868 W of single-wavelength output at 1050 nm with an optical-to-optical (O–O) conversion efficiency of 8.9%, exhibiting excellent power stability (RMS < 0.6%). When it was switched to a dual-wavelength operation at 1030 nm and 1050 nm, the total output power reached 0.376 W with respective powers of 0.180 W (1030 nm) and 0.196 W (1050 nm), corresponding to a 1.792% O–O conversion efficiency and a power stability of RMS < 3.0%. When it was switched to single-wavelength operation at 1030 nm, the maximum output power reached 0.193 W with a 0.920% O–O conversion efficiency and a power stability of RMS < 1.5%. These experimental results confirm that the controlled modulation of geometric losses in a dual-confocal resonator provides an effective approach for achieving flexible wavelength switching while maintaining stable output performance. This methodology offers promising potential for expanding the application scope of dual-wavelength lasers in precision optical systems. Full article
►▼ Show Figures

Figure 1

11 pages, 5491 KB  
Article
A 5 kW Near-Single-Mode Oscillating–Amplifying Fiber Laser Employing a Broadband Output Coupler with Simultaneous Raman Suppression and Spectral Narrowing
by Jiazheng Wu, Miao Yu, Yi Cao, Shiqi Jiang, Shihao Sun and Junlong Wang
Photonics 2025, 12(8), 813; https://doi.org/10.3390/photonics12080813 - 14 Aug 2025
Viewed by 425
Abstract
In this work, we propose and demonstrate a novel approach to suppressing stimulated Raman scattering in an oscillating–amplifying integrated fiber laser (OAIFL) by changing the spectral bandwidth of the output-coupler fiber Bragg gratings (OC-FBGs). The reflectance bandwidth of the fiber Bragg grating (FBG) [...] Read more.
In this work, we propose and demonstrate a novel approach to suppressing stimulated Raman scattering in an oscillating–amplifying integrated fiber laser (OAIFL) by changing the spectral bandwidth of the output-coupler fiber Bragg gratings (OC-FBGs). The reflectance bandwidth of the fiber Bragg grating (FBG) in the oscillating section was systematically investigated as a critical parameter for SRS mitigation. Three types of long-period FBGs with distinct reflectance bandwidths (1.2 nm, 1.3 nm, and 2 nm) were comparatively studied as output couplers. The experimental results demonstrated a direct correlation between FBG bandwidth and SRS suppression efficiency, with the configuration of the OC-FBG with a 2 nm bandwidth achieving optimal suppression performance. Concurrently, the output power was enhanced to 5.02 kW with improved power scalability. And excellent beam quality was obtained with M2 < 1.3. Remarkably, in the architecture of this laser, increasing the bandwidth of the output couplers in the oscillating section had a relatively minor effect on the optical-to-optical (O-O) efficiency, which reached up to 78%. Additionally, this modification also reduced the 3 dB bandwidth of the laser output, thereby achieving a beam output with enhanced monochromaticity. Full article
(This article belongs to the Special Issue High-Power Fiber Lasers)
►▼ Show Figures

Figure 1

10 pages, 2113 KB  
Article
Generation of 27 nm Spectral Bandwidth, Two-Port Output Pulses Directly from a Yb-Doped Fiber Laser
by Junyu Chen, Mengyun Hu, Jianing Chen, Chixuan Zou, Zichen Zhao, Gantong Zhong and Shuai Yuan
Photonics 2025, 12(8), 812; https://doi.org/10.3390/photonics12080812 - 14 Aug 2025
Viewed by 377
Abstract
We reported on a generation of 27 nm spectral bandwidth, two-port output ultrashort pulses directly from an all-normal-dispersion passively mode-locked Yb-fiber laser. Based on the nonlinear polarization rotation (NPR) mode-locking technique, high pump power and optical devices with high damage thresholds were introduced [...] Read more.
We reported on a generation of 27 nm spectral bandwidth, two-port output ultrashort pulses directly from an all-normal-dispersion passively mode-locked Yb-fiber laser. Based on the nonlinear polarization rotation (NPR) mode-locking technique, high pump power and optical devices with high damage thresholds were introduced to achieve broad spectral bandwidth and strong output power. The dual wavelengths were emitted from the clockwise and counterclockwise ports, respectively, and self-started mode-locking was achieved. The bidirectional output laser generates stable pulses with up to 223.5 mW average power at a 46.04 MHz repetition rate, corresponding to a pulse energy of 5 nJ. The bidirectional ultrashort outputs of the laser provide potential applications in supercontinuum generation and medical and biological applications. Full article
(This article belongs to the Special Issue Advances in Ultrafast Laser Science and Applications)
►▼ Show Figures

Figure 1

9 pages, 1337 KB  
Communication
Photonic–Surface Plasmon Coupling Mode: Experimental Study with a Silver Thin-Film Coating on MPCC
by Pengfei Li, Zhanwu Xie, Haitao Yan and Shitong Zhong
Photonics 2025, 12(8), 811; https://doi.org/10.3390/photonics12080811 - 13 Aug 2025
Viewed by 309
Abstract
In this paper, a silver thin film coating on a monolayer polystyrene colloidal crystal (MPCC) hybrid structure was fabricated, and a photonic–surface plasmon coupling mode was established and experimentally researched. The silver thin film was sputtered onto the MPCC to form Ag-MPCC. The [...] Read more.
In this paper, a silver thin film coating on a monolayer polystyrene colloidal crystal (MPCC) hybrid structure was fabricated, and a photonic–surface plasmon coupling mode was established and experimentally researched. The silver thin film was sputtered onto the MPCC to form Ag-MPCC. The silver film effectively excites surface plasmon polariton (SPP) modes upon the incidence of light, and the MPCC has an intrinsic mode. These two modes couple and result in the extraordinary optical transmission (EOT) phenomenon in the transmission spectrum. Reflection suppression arising from this photon coupling effect was discovered in the reflection spectrum. We etched the single-layer colloidal particles to change the period of the colloidal crystal, thereby forming the MPCC metal hybrid structure with different lattices. We discussed and analyzed the results through experiments. The EOT can be controlled by the incident angle, lattice periodicity, and refractive index distribution of the Ag-MPCC, and the diffraction behavior is determined using the lattice structure and refractive index of the MPCC. The coupling effect of the two models leads to wavelength shifts and intensity variations in the spectral eigenvalues. Reflection suppression is achieved when the reflectivity at a specific wavelength is close to 0.1. Full article
►▼ Show Figures

Figure 1

31 pages, 3840 KB  
Review
Application of Deep Learning in the Phase Processing of Digital Holographic Microscopy
by Wenbo Jiang, Lirui Liu and Yun Bu
Photonics 2025, 12(8), 810; https://doi.org/10.3390/photonics12080810 - 13 Aug 2025
Viewed by 462
Abstract
Digital holographic microscopy (DHM) provides numerous advantages, such as noninvasive sample analysis, real-time dynamic detection, and three-dimensional (3D) reconstruction, making it a valuable tool in fields such as biomedical research, cell mechanics, and environmental monitoring. To achieve more accurate and comprehensive imaging, it [...] Read more.
Digital holographic microscopy (DHM) provides numerous advantages, such as noninvasive sample analysis, real-time dynamic detection, and three-dimensional (3D) reconstruction, making it a valuable tool in fields such as biomedical research, cell mechanics, and environmental monitoring. To achieve more accurate and comprehensive imaging, it is crucial to capture detailed information on the microstructure and 3D morphology of samples. Phase processing of holograms is essential for recovering phase information, thus making it a core component of DHM. Traditional phase processing techniques often face challenges, such as low accuracy, limited robustness, and poor generalization. Recently, with the ongoing advancements in deep learning, addressing phase processing challenges in DHM has become a key research focus. This paper provides an overview of the principles behind DHM and the characteristics of each phase processing step. It offers a thorough analysis of the progress and challenges of deep learning methods in areas such as phase retrieval, filtering, phase unwrapping, and distortion compensation. The paper concludes by exploring trends, such as ultrafast 3D holographic reconstruction, high-throughput holographic data analysis, multimodal data fusion, and precise quantitative phase analysis. Full article
(This article belongs to the Special Issue Holographic Information Processing)
►▼ Show Figures

Figure 1

36 pages, 3275 KB  
Review
Research Progress of Surface-Enhanced Raman Scattering (SERS) Technology in Food, Biomedical, and Environmental Monitoring
by Rui-Song Xue, Jia-Yi Dai, Xue-Jiao Wang and Ming-Yang Chen
Photonics 2025, 12(8), 809; https://doi.org/10.3390/photonics12080809 - 13 Aug 2025
Viewed by 813
Abstract
Surface-enhanced Raman scattering (SERS) technology, leveraging its single-molecule-level detection sensitivity, molecular fingerprint recognition capability, and capacity for rapid, non-destructive analysis, has emerged as a pivotal analytical tool in food science, life sciences, and environmental monitoring. This review systematically summarizes recent advancements in SERS [...] Read more.
Surface-enhanced Raman scattering (SERS) technology, leveraging its single-molecule-level detection sensitivity, molecular fingerprint recognition capability, and capacity for rapid, non-destructive analysis, has emerged as a pivotal analytical tool in food science, life sciences, and environmental monitoring. This review systematically summarizes recent advancements in SERS technology, encompassing its enhancement mechanisms (synergistic effects of electromagnetic and chemical enhancement), innovations in high-performance substrates (noble metal nanostructures, non-noble metal substrates based on semiconductors/graphene, and hybrid systems incorporating noble metals with functional materials), and its interdisciplinary applications. In the realm of food safety, SERS has enabled the ultratrace detection of pesticide residues, mycotoxins, and heavy metals, with flexible substrates and intelligent algorithms significantly enhancing on-site detection capabilities. Within biomedicine, the technique has been successfully applied to the rapid identification of pathogenic microorganisms, screening of tumor biomarkers, and viral diagnostics. For environmental monitoring, SERS platforms offer sensitive detection of heavy metals, microplastics, and organic pollutants. Despite challenges such as matrix interference and insufficient substrate reproducibility, future research directions aimed at developing multifunctional composite materials, integrating artificial intelligence algorithms, constructing portable devices, and exploring plasmon-catalysis synergy are poised to advance the practical implementation of SERS technology in precision diagnostics, intelligent regulation, and real-time monitoring. Full article
(This article belongs to the Section Biophotonics and Biomedical Optics)
►▼ Show Figures

Figure 1

16 pages, 2415 KB  
Review
Recycling Technologies for Extracting Gallium from Light-Emitting Diodes
by Laraib Mustafa, Muhammad Usman, Shazma Ali, Ahmed Ali and Anis Naveed
Photonics 2025, 12(8), 808; https://doi.org/10.3390/photonics12080808 - 12 Aug 2025
Viewed by 561
Abstract
Light-emitting diodes (LEDs) are made up of precious metals, e.g., gallium. These elements can be recovered and reused, reducing the need for new raw materials. Proper recycling prevents harmful substances in LEDs, such as lead and arsenic, from contaminating the environment. Recycling LEDs [...] Read more.
Light-emitting diodes (LEDs) are made up of precious metals, e.g., gallium. These elements can be recovered and reused, reducing the need for new raw materials. Proper recycling prevents harmful substances in LEDs, such as lead and arsenic, from contaminating the environment. Recycling LEDs uses less energy compared to producing new ones, leading to lower carbon emissions. The valuable metal gallium faces the challenge of supply and demand due to the surge in its demand, the difficulty of separating it from minerals, and processing issues during extraction. In this review, we describe the methods for recycling gallium from LEDs by using different techniques such as pyrolysis (95% recovery), oxalic acid leaching (83.2% recovery), HCL acid leaching of coal fly ash (90–95% recovery), subcritical water treatment (80.5% recovery), supercritical ethanol (93.10% recovery), oxidation and subsequent leaching (91.4% recovery), and vacuum metallurgy separation (90% recovery). Based on our analysis, hydrometallurgy is the best approach for recovering gallium. It is reported that approximately 5% of the waste from LEDs is adequately recycled, whereas the total gallium potential wasted throughout production is over 93%. By recycling LEDs, we can minimize waste, conserve resources, and promote sustainable practices. Thus, recycling LEDs is essential for strengthening a circular economy. Full article
(This article belongs to the Special Issue Light-Emitting Diodes: Technology, Advances, Challenges and Applications)
►▼ Show Figures

Figure 1

13 pages, 2876 KB  
Article
Comparative Study of Raman Laser Generation Techniques in Cold Atomic Gravimeters
by Rui Xu, Fangjun Qin, Zhichao Ding, Hao Chen, An Li, Dongyi Li, Jiaqing Sun, Haibo Zhang and Chenxi Ge
Photonics 2025, 12(8), 807; https://doi.org/10.3390/photonics12080807 - 11 Aug 2025
Viewed by 351
Abstract
In the measurement process of cold atomic gravimeters, Raman laser plays an important role both in the state preparation stage and in the atomic interference stage. This paper discusses Raman laser generation techniques. The optical phase-locked loop (OPLL) method and the electro-optical modulation [...] Read more.
In the measurement process of cold atomic gravimeters, Raman laser plays an important role both in the state preparation stage and in the atomic interference stage. This paper discusses Raman laser generation techniques. The optical phase-locked loop (OPLL) method and the electro-optical modulation (EOM) method are compared from a theoretical point of view. An OPLL system and an EOM system were constructed separately. The two schemes were tested in terms of linewidth, phase noise and long-term stability. The experimental results were analyzed and discussed. Based on the results, recommendations are given for the selection of Raman laser schemes under different scenarios. Full article
(This article belongs to the Section New Applications Enabled by Photonics Technologies and Systems)
►▼ Show Figures

Figure 1

13 pages, 3051 KB  
Article
Impact of LD Spectra on Efficiency of Yb-Doped Fiber Laser
by Fengyun Li, Yi Shi, Chun Zhang, Qiuhui Chu, Lingli Huang, Haoyu Zhang, Qiang Shu, Yu Wen, Xingchen Jiang, Zixiang Gao, Honghuan Lin and Rumao Tao
Photonics 2025, 12(8), 806; https://doi.org/10.3390/photonics12080806 - 11 Aug 2025
Viewed by 333
Abstract
The spectral characteristics of pump laser diodes (LDs) introduce significant ambiguity into the performance evaluation of high-power ytterbium-doped fiber lasers (YDFLs), obscuring their intrinsic efficiency and hindering reliable system design. Here, we introduce a rigorous quantitative framework that decouples these pump-induced effects by [...] Read more.
The spectral characteristics of pump laser diodes (LDs) introduce significant ambiguity into the performance evaluation of high-power ytterbium-doped fiber lasers (YDFLs), obscuring their intrinsic efficiency and hindering reliable system design. Here, we introduce a rigorous quantitative framework that decouples these pump-induced effects by referencing laser performance to the absorbed, rather than the launched, pump power. Our analysis demonstrates that the widely reported discrepancies in conventional optical-to-optical (OO) and slope efficiencies are governed almost entirely by variations in pump absorption, while the influence of the quantum defect is negligible. This approach provides a robust metric for intrinsic laser performance that is independent of the LD’s spectral properties, proving particularly valuable for systems pumped by non-wavelength-stabilized LDs (nWS-LDs). We uncover a non-monotonic evolution of the unabsorbed residual pump power, revealing that the peak thermal load on system components occurs at an intermediate operational state, not at maximum pump power. This finding challenges conventional thermal management strategies and is critical for ensuring the long-term operational reliability of high-power YDFLs. Full article
(This article belongs to the Special Issue Advancements in High-Power Optical Fibers and Fiber Lasers)
►▼ Show Figures

Figure 1

14 pages, 2038 KB  
Article
Electro-Optic Toffoli Logic Based on Hybrid Surface Plasmons
by Zhixun Liang, Yunying Shi, Yunfei Yi and Yuanyuan Fan
Photonics 2025, 12(8), 805; https://doi.org/10.3390/photonics12080805 - 11 Aug 2025
Viewed by 256
Abstract
Reversible gates theoretically do not result in energy loss during the calculation process. The Toffoli gate is a universal reversible logic gate, and any reversible circuit can be constructed from the Toffoli gate. This paper presents a hybrid electro-optic Toffoli logic that uses [...] Read more.
Reversible gates theoretically do not result in energy loss during the calculation process. The Toffoli gate is a universal reversible logic gate, and any reversible circuit can be constructed from the Toffoli gate. This paper presents a hybrid electro-optic Toffoli logic that uses an HSPP Switch (hybrid surface plasmon polariton switch), waveguide coupler, and Y-shaped splitter. The hybrid electro-optic Toffoli logic operation is applied via voltage regulation, and the FDTD simulation is used for this research. The modeling and simulation results show that the device’s operating speed is up to 61.62 GHz; the power consumption for transmitting 1 bit is only 13.44 fJ; the average insertion loss is 6.4 dB, and the average extinction ratio of each output port is 19.7 dB. Full article
(This article belongs to the Special Issue Thermal Radiation and Micro-/Nanophotonics)
►▼ Show Figures

Figure 1

12 pages, 2763 KB  
Article
Damage Characteristics of Silicon Solar Cells Induced by Nanosecond Pulsed Laser
by Hao Chang, Weijing Zhou, Yingjie Ma, Zhilong Jian, Xiaoyuan Quan and Chenyu Xiao
Photonics 2025, 12(8), 804; https://doi.org/10.3390/photonics12080804 - 11 Aug 2025
Viewed by 309
Abstract
The damage characteristics of monocrystalline silicon solar cells irradiated by a nanosecond pulsed laser were investigated in a vacuum environment. An 8 ns pulsed laser was used with a 1064 nm wavelength, a 2.0 J maximum pulse energy, and a millimeter-scale ablation spot [...] Read more.
The damage characteristics of monocrystalline silicon solar cells irradiated by a nanosecond pulsed laser were investigated in a vacuum environment. An 8 ns pulsed laser was used with a 1064 nm wavelength, a 2.0 J maximum pulse energy, and a millimeter-scale ablation spot diameter. The cells were irradiated by a laser with varying fluences, irradiation positions, and pulse numbers. The damage mechanism was discussed in combination with the degradation of electrical properties, the morphology of surface damage, and electroluminescence images. A single pulse mainly caused surface heating and deformation, while multi-pulse irradiation led to the formation of melting ablation craters. More severe performance degradation was caused by irradiation at the grid line site due to fracture of the grid line electrodes. Moreover, monocrystalline silicon cells showed excellent damage resistance to fixed-position irradiations at non-gridded line areas. This work reveals, for the first time in vacuum, that grid-line fracture dominates performance degradation—enabling targeted hardening for space solar cells. Full article
►▼ Show Figures

Figure 1

17 pages, 2652 KB  
Article
First-Principles and Device-Level Investigation of β-AgGaO2 Ferroelectric Semiconductors for Photovoltaic Applications
by Wen-Jie Hu, Xin-Yu Zhang, Xiao-Tong Zhu, Yan-Li Hu, Hua-Kai Xu, Xiang-Fu Xu, You-Da Che, Xing-Yuan Chen, Li-Ting Niu and Bing Dai
Photonics 2025, 12(8), 803; https://doi.org/10.3390/photonics12080803 - 11 Aug 2025
Viewed by 345
Abstract
Ferroelectric semiconductors, with their inherent spontaneous polarization, present a promising approach for efficient charge separation, making them attractive for photovoltaic applications. The potential of β-AgGaO2, a polar ternary oxide with an orthorhombic Pna21 structure, as a light-absorbing material is evaluated. [...] Read more.
Ferroelectric semiconductors, with their inherent spontaneous polarization, present a promising approach for efficient charge separation, making them attractive for photovoltaic applications. The potential of β-AgGaO2, a polar ternary oxide with an orthorhombic Pna21 structure, as a light-absorbing material is evaluated. First-principles computational analysis reveals that β-AgGaO2 possesses an indirect bandgap of 2.1 eV and exhibits pronounced absorption within the visible spectral range. Optical simulations suggest that a 300 nm thick absorber layer could theoretically achieve a power conversion efficiency (PCE) of 20%. Device-level simulations using SCAPS-1D evaluate the influence of hole and electron transport layers on solar cell performance. Among the tested hole transport materials, Cu2FeSnS4 (CFTS) achieves the highest PCE of 14%, attributed to its optimized valence band alignment and reduced recombination losses. In contrast, no significant improvements were observed with the electron transport layers tested. These findings indicate the potential of β-AgGaO2 as a ferroelectric photovoltaic absorber and emphasize the importance of band alignment and interface engineering for optimizing device performance. Full article
►▼ Show Figures

Figure 1

9 pages, 1588 KB  
Communication
Sub-60 fs, 1300 nm Laser Pulses Generation from Soliton Self-Frequency Shift Pumped by Femtosecond Yb-Doped Fiber Laser
by Hongyuan Xuan, Kong Gao, Xingyang Zou, Ze Zhang, Wenchao Qiao and Yizhou Liu
Photonics 2025, 12(8), 802; https://doi.org/10.3390/photonics12080802 - 10 Aug 2025
Viewed by 426
Abstract
We report on the generation of 1300 nm ultrashort laser pulses via the soliton self-frequency shift in a high-nonlinearity fiber, pumped by the 41.9 MHz, 67.9 fs, 1073 nm femtosecond laser emitted from an Yb-doped fiber laser system. A numerical simulation was applied [...] Read more.
We report on the generation of 1300 nm ultrashort laser pulses via the soliton self-frequency shift in a high-nonlinearity fiber, pumped by the 41.9 MHz, 67.9 fs, 1073 nm femtosecond laser emitted from an Yb-doped fiber laser system. A numerical simulation was applied to investigate the spectral broadening process driven by the soliton self-frequency shift with increased pump power. The experimental results are in good agreement with the numerical results, delivering a 33 mW, 57.8 fs 1300 nm Raman soliton filtered by a longpass filter. The impact of the polarization direction of the injected pump laser on the soliton self-frequency shift process was also further investigated. The root means squares of the Yb-doped fiber laser and the nonlinearly spectral broadened laser were 0.19%@1h and 0.23%@1h, respectively. Full article
(This article belongs to the Special Issue Ultrafast Optics: From Fundamental Dynamics to Transformative Technologies)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-92
Previous Issue
Next Issue
Back to TopTop