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
Far-Field Super-Resolution Microscopy Using Evanescent Illumination: A Review
Photonics 2024, 11(6), 528; https://doi.org/10.3390/photonics11060528 (registering DOI) - 1 Jun 2024
Abstract
The resolution of conventional optical microscopy is restricted by the diffraction limit. Light waves containing higher-frequency information about the sample are bound to the sample surface and cannot be collected by far-field optical microscopy. To break the resolution limit, researchers have proposed various
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The resolution of conventional optical microscopy is restricted by the diffraction limit. Light waves containing higher-frequency information about the sample are bound to the sample surface and cannot be collected by far-field optical microscopy. To break the resolution limit, researchers have proposed various far-field super-resolution (SR) microscopy imaging methods using evanescent waves to transfer the high-frequency information of samples to the low-frequency passband of optical microscopy. Optimization algorithms are developed to reconstruct a SR image of the sample by utilizing the high-frequency information. These techniques can be collectively referred to as spatial-frequency-shift (SFS) SR microscopy. This review aims to summarize the basic principle of SR microscopy using evanescent illumination and introduce the advances in this research area. Some current challenges and possible directions are also discussed.
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(This article belongs to the Special Issue Super Resolution Optical Microscopy: Sensing and Imaging)
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A Terahertz Programmable Digital Metasurface Based on Vanadium Dioxide
by
Tianrui Pan, Chenxi Liu, Shuang Peng, Haiying Lu, Han Zhang, Xiaoming Xu and Fei Yang
Photonics 2024, 11(6), 527; https://doi.org/10.3390/photonics11060527 (registering DOI) - 1 Jun 2024
Abstract
Metasurfaces can realize the flexible manipulation of electromagnetic waves, which have the advantages of a low profile and low loss. In particular, the coding metasurface can flexibly manipulate electromagnetic waves through controllable sequence encoding of the coding units to achieve different functions. In
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Metasurfaces can realize the flexible manipulation of electromagnetic waves, which have the advantages of a low profile and low loss. In particular, the coding metasurface can flexibly manipulate electromagnetic waves through controllable sequence encoding of the coding units to achieve different functions. In this paper, a three−layer active coding metasurface is designed based on vanadium dioxide ( ), which has an excellent phase transition. For the designed unit cell, the top patterned layer is composed of two split square resonant rings (SSRRs), whose gaps are in opposite directions, and each SSRR is composed of gold and . When changes from the dielectric state to the metal state, the resonant mode changes from microstrip resonance to LC resonance, correspondingly. According to the Pancharatnam−Berry (P−B) phase, the designed metasurface can actively control terahertz circularly polarized waves in the near field. The metasurface can manipulate the order of the generated orbital angular momentum (OAM) beams: when the dielectric changes to metal , the order l of the OAM beams generated by the metasurface changes from −1 to −2, and the purity of the generated OAM beams is relatively high. It is expected to have important application values in terahertz wireless communication, radar, and other fields.
Full article
(This article belongs to the Special Issue Emerging Trends in Metamaterials and Metasurfaces Research)
Open AccessArticle
Shallow Trench Isolation Patterning to Improve Photon Detection Probability of Single-Photon Avalanche Diodes Integrated in FD-SOI CMOS Technology
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Shaochen Gao, Duc-Tung Vu, Thibauld Cazimajou, Patrick Pittet, Martine Le Berre, Mohammadreza Dolatpoor Lakeh, Fabien Mandorlo, Régis Orobtchouk, Jean-Baptiste Schell, Jean-Baptiste Kammerer, Andreia Cathelin, Dominique Golanski, Wilfried Uhring and Francis Calmon
Photonics 2024, 11(6), 526; https://doi.org/10.3390/photonics11060526 (registering DOI) - 1 Jun 2024
Abstract
The integration of Single-Photon Avalanche Diodes (SPADs) in CMOS Fully Depleted Silicon-On-Insulator (FD-SOI) technology under a buried oxide (BOX) layer and a silicon film containing transistors makes it possible to realize a 3D SPAD at the chip level. In our study, a nanostructurated
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The integration of Single-Photon Avalanche Diodes (SPADs) in CMOS Fully Depleted Silicon-On-Insulator (FD-SOI) technology under a buried oxide (BOX) layer and a silicon film containing transistors makes it possible to realize a 3D SPAD at the chip level. In our study, a nanostructurated layer created by an optimized arrangement of Shallow Trench Isolation (STI) above the photosensitive zone generates constructive interferences and consequently an increase in the light sensitivity in the frontside illumination. A simulation methodology is presented that couples electrical and optical data in order to optimize the STI trenches (size and period) and to estimate the Photon Detection Probability (PDP) gain. Then, a test chip was designed, manufactured, and characterized, demonstrating the PDP improvement due to the STI nanostructuring while maintaining a comparable Dark Count Rate (DCR).
Full article
(This article belongs to the Special Issue Emerging Topics in Single-Photon Detectors)
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A Near Fourier-Limited Pulse-Preserving Monochromator for Extreme-Ultraviolet Pulses in the Few-Fs Regime
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Yudong Yang, Tanja Neumann, Julia Hengster, Roland E. Mainz, Jakob Elsner, Oliver D. Mücke, Franz X. Kärtner and Thorsten Uphues
Photonics 2024, 11(6), 525; https://doi.org/10.3390/photonics11060525 (registering DOI) - 1 Jun 2024
Abstract
We present a pulse-preserving multilayer-based extreme-ultraviolet (XUV) monochromator providing ultra-narrow bandwidth ( , ) and compact footprint ( ) for easy integration into high-harmonic generation (HHG) or free-electron
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We present a pulse-preserving multilayer-based extreme-ultraviolet (XUV) monochromator providing ultra-narrow bandwidth ( , ) and compact footprint ( ) for easy integration into high-harmonic generation (HHG) or free-electron laser (FEL) sources. The temporal resolution of the novel design supports pulse durations of typical pump–probe setups in the femtosecond and attosecond regime, depending on the mirror design and focusing geometries over the tuning range of the monochromator. The theoretical design is analyzed and experimentally characterized in a laser-driven HHG setup.
Full article
(This article belongs to the Special Issue Advances in Ultrafast Optics: From Fundamental Science to Applications)
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Open AccessArticle
A Comprehensive Study on Elasticity and Viscosity in Biomechanics and Optical Properties of the Living Human Cornea
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Francisco J. Ávila, Óscar del Barco, María Concepción Marcellán and Laura Remón
Photonics 2024, 11(6), 524; https://doi.org/10.3390/photonics11060524 - 31 May 2024
Abstract
Corneal biomechanics is a hot topic in ophthalmology. The biomechanical properties (BMPs) of the cornea have important implications in the management and diagnosis of corneal diseases such as ectasia and keratoconus. In addition, the characterization of BMPs is crucial to model the predictability
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Corneal biomechanics is a hot topic in ophthalmology. The biomechanical properties (BMPs) of the cornea have important implications in the management and diagnosis of corneal diseases such as ectasia and keratoconus. In addition, the characterization of BMPs is crucial to model the predictability of a corneal surgery intervention, the outcomes of refractive surgery or the follow-up of corneal diseases. The biomechanical behavior of the cornea is governed by viscoelastic properties that allow, among other structural implications, the damping of excess intraocular pressure and the reduction of damage to the optic nerve. Currently, the most versatile and complete methods to measure corneal viscoelasticity are based on air-puff corneal applanation. However, these methods lack the ability to directly measure corneal viscosity. The aim of this work is to propose a new methodology based on the analysis of corneal air-puff measurements through the standard linear solid model (SLSM) to provide analytical expressions to separately calculate the elastic and time-dependent (corneal retardation time and viscosity) properties. The results show the mean values of elasticity (E), viscosity (Ƞ) and corneal retardation time (τ) in a sample of 200 young and healthy subjects. The influence of elasticity and viscosity on viscoelasticity, high-order corneal aberrations and optical transparency is investigated. Finally, the SLSM fed back from experimental E and Ƞ values is employed to compare the creep relaxation response between a normal, an ocular hypertension patient and an Ortho-K user. Corneal biomechanics is strongly affected by intraocular pressure (IOP); however, corneal hysteresis (CH) analysis is not enough to be employed as a risk factor of glaucoma progression. Low values of CH can be accompanied by high or low corneal elasticity and viscosity depending on the IOP threshold from which the time-dependent biomechanical properties trends are reversed.
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(This article belongs to the Special Issue Visual Optics)
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Open AccessArticle
Advanced Various Fault Detection Scheme for Long-Reach Mode Division Multiplexing Transmission
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Feng Liu, Zicheng Huang and Tianle Gu
Photonics 2024, 11(6), 523; https://doi.org/10.3390/photonics11060523 - 30 May 2024
Abstract
This paper presents a few-mode fiber (FMF) various fault-detection method for long-reach mode division multiplexing (MDM) based on multi-mode transmission reflection analysis (MM-TRA). By injecting unmodulated continuous light into the FMF, and measuring and quantitatively analyzing the transmitted and reflected or Rayleigh backscattering
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This paper presents a few-mode fiber (FMF) various fault-detection method for long-reach mode division multiplexing (MDM) based on multi-mode transmission reflection analysis (MM-TRA). By injecting unmodulated continuous light into the FMF, and measuring and quantitatively analyzing the transmitted and reflected or Rayleigh backscattering power of different spatial modes, it is possible to accurately detect and locate reflective and non-reflective fault events. This paper discusses the localization accuracy of fault types such as FMF break, FMF link connector mismatch, and FMF bending. Theoretical analysis and simulation experimental results demonstrate that the proposed MM-TRA can provide an effective characterization of various faults and can achieve high fault localization accuracy. In addition, the influence of mode crosstalk of mode multiplexer/demultiplexer and mode coupling in FMF on the localization accuracy of various faults are considered. The results indicate that when using the combination of LP01 and LP21 modes, the localization errors for the FMF break, connector mismatch, and bending are 3.42 m, 1.97 m, and 3.29 m, respectively, demonstrating good fault localization performance.
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(This article belongs to the Section Lasers, Light Sources and Sensors)
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Open AccessReview
High-Resolution Retinal Imaging: Technology Overview and Applications
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Mircea Mujat, R. Daniel Ferguson, Daniel X. Hammer, Ankit H. Patel and Nicusor Iftimia
Photonics 2024, 11(6), 522; https://doi.org/10.3390/photonics11060522 - 30 May 2024
Abstract
Adaptive optics (AO) has been used in many applications, including astronomy, microscopy, and medical imaging. In retinal imaging, AO provides real-time correction of the aberrations introduced by the cornea and the lens to facilitate diffraction-limited imaging of retinal microstructures. Most importantly, AO-based retinal
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Adaptive optics (AO) has been used in many applications, including astronomy, microscopy, and medical imaging. In retinal imaging, AO provides real-time correction of the aberrations introduced by the cornea and the lens to facilitate diffraction-limited imaging of retinal microstructures. Most importantly, AO-based retinal imagers provide cellular-level resolution and quantification of changes induced by retinal diseases and systemic diseases that manifest in the eye enabling disease diagnosis and monitoring of disease progression or the efficacy of treatments. In this paper, we present an overview of our team efforts over almost two decades to develop high-resolution retinal imagers suitable for clinical use. Several different types of imagers for human and small animal eye imaging are reviewed, and representative results from multiple studies using these instruments are shown. These examples demonstrate the extraordinary power of AO-based retinal imaging to reveal intricate details of morphological and functional characteristics of the retina and to help elucidate important aspects of vision and of the disruptions that affect delicate retinal tissue.
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(This article belongs to the Special Issue Adaptive Optics: Methods and Applications)
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Period-Doubling Route to Chaos in Photorefractive Two-Wave Mixing
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Subin Saju, Kenji Kinashi, Naoto Tsutsumi, Wataru Sakai and Boaz Jessie Jackin
Photonics 2024, 11(6), 521; https://doi.org/10.3390/photonics11060521 - 29 May 2024
Abstract
This paper investigates the possibilities of complex nonlinear dynamic signal generation using a simple photorefractive two-wave mixing system without any feedback using numerical simulations. The novel idea is to apply a sinusoidal electric field to the system inroder to extract nonlinear dynamic behavior.
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This paper investigates the possibilities of complex nonlinear dynamic signal generation using a simple photorefractive two-wave mixing system without any feedback using numerical simulations. The novel idea is to apply a sinusoidal electric field to the system inroder to extract nonlinear dynamic behavior. The mathematical model of the system was constructed using Kogelnick’s coupled wave equations and Kukhtarev’s material equation. The spatio-temporal evolution of the system was simulated in discrete steps numerically. The temporal evolution of the output light intensity exhibits period doubling, behavior which is a characteristic feature of complex nonlinear dynamic systems. A bifurcation diagram and Lyapunov exponentials confirm the presence of the period-doubling route to chaos in the system. The observed complex signal pattern varies uniformly with respect to the amplitude of the applied field, indicating a controllable nonlinear dynamic behavior. Such a system can be very useful in applications such as photonic reservoir computing, in-materio computing, photonic neuromorphic networks, complex signal detection, and time series prediction.
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(This article belongs to the Special Issue State-of-the-Art in Optical Materials)
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Open AccessCommunication
Four-Fold, Cross-Phase Modulation Driven UV Pulse Compression in a Thin Bulk Medium
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Peter Susnjar, Alexander Demidovich, Gabor Kurdi, Paolo Cinquegrana, Ivaylo Nikolov, Paolo Sigalotti and Miltcho B. Danailov
Photonics 2024, 11(6), 520; https://doi.org/10.3390/photonics11060520 - 28 May 2024
Abstract
Generation of high energy few-fs pulses in the ultraviolet (UV) still represents challenges due to compression and phase control difficulties in this spectral range. Presented here is a pulse compression approach utilizing cross-phase modulation within a thin solid-state medium induced by a strong,
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Generation of high energy few-fs pulses in the ultraviolet (UV) still represents challenges due to compression and phase control difficulties in this spectral range. Presented here is a pulse compression approach utilizing cross-phase modulation within a thin solid-state medium induced by a strong, spatially and temporally controllable near-infrared (NIR) pulse acting on a weaker, 400 nm UV pulse. Through this method, four-fold compression is attained within a single fused silica plate, resulting in a 13 fs UV pulse with preserved beam quality. With some further technical adjustments, this method’s applicability could be extended to deep or even vacuum UV, where direct compression is difficult.
Full article
(This article belongs to the Special Issue Recent Progress in Ultrafast Laser)
Open AccessArticle
Unraveling Electronic and Vibrational Coherences Following a Charge Transfer Process in a Photosystem II Reaction Center
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Junhua Zhou, Xuanchao Zhang, Vandana Tiwari, Chao Mei, Ajay Jha, Pan-Pan Zhang and Hong-Guang Duan
Photonics 2024, 11(6), 519; https://doi.org/10.3390/photonics11060519 - 28 May 2024
Abstract
A reaction center is a unique biological system that performs the initial charge separation within a Photosystem II (PSII) multiunit enzyme, which eventually drives the catalytic water-splitting in plants and algae. The possible role of quantum coherences coinciding with the energy and charge
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A reaction center is a unique biological system that performs the initial charge separation within a Photosystem II (PSII) multiunit enzyme, which eventually drives the catalytic water-splitting in plants and algae. The possible role of quantum coherences coinciding with the energy and charge transfer processes in PSII reaction center is one of the active areas of research. Here, we study these quantum coherences by using a numerically exact method on an excitonic dimer model, including linear vibronic coupling and employing optimal parameters from experimental two-dimensional coherent spectroscopic measurements. This enables us to precisely capture the excitonic interaction between pigments and the dissipation of the energy from electronic and charge-transfer (CT) states to the protein environment. We employ the time nonlocal (TNL) quantum master equation to calculate the population dynamics, which yields numerically reliable results. The calculated results show that, due to the strong dissipation, the lifetime of electronic coherence is too short to have direct participation in the charge transfer processes. However, there are long-lived vibrational coherences present in the system at frequencies close to the excitionic energy gap. These are strongly coupled with the electronic coherences, which makes the detection of the electronic coherences with conventional techniques very challenging. Additionally, we unravel the strong excitonic interaction of radical pair ( and ) in the reaction center, which results in a long-lived electronic coherence of >100 fs, even at room temperature. Our work provide important physical insight to the charge separation process in PSII reaction center, which may be helpful for better understanding of photophysical processes in other natural and artificial light-harvesting systems.
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(This article belongs to the Section Lasers, Light Sources and Sensors)
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Compact Single-Shot Dual-Wavelength Interferometry for Large Object Measurement with Rough Surfaces
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Yizhang Yan, Suhas P. Veetil, Pengfei Zhu, Feng Gao, Yan Kong, Xiaoliang He, Aihui Sun, Zhilong Jiang and Cheng Liu
Photonics 2024, 11(6), 518; https://doi.org/10.3390/photonics11060518 - 28 May 2024
Abstract
Single-shot dual-wavelength interferometry offers a promising avenue for surface profile measurement of dynamic objects. However, current techniques employing pixel multiplexing or color cameras encounter challenges such as complex optical alignment, limited measurement range, and difficulty in measuring rough surfaces. To address these issues,
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Single-shot dual-wavelength interferometry offers a promising avenue for surface profile measurement of dynamic objects. However, current techniques employing pixel multiplexing or color cameras encounter challenges such as complex optical alignment, limited measurement range, and difficulty in measuring rough surfaces. To address these issues, this study presents a novel approach to single-shot dual-wavelength interferometry. By utilizing separated polarization illumination and detection, along with a monochromatic polarization camera and two slightly different wavelengths, this method enables the simultaneous recording of two frames of separated interferometric patterns. This approach facilitates straightforward optical alignment, expands measurement ranges, accelerates data acquisition, and simplifies data processing for dual-wavelength interferometry. Consequently, it enables online shape measurement of large dynamic samples with rough surfaces.
Full article
(This article belongs to the Special Issue Recent Advances in 3D Optical Measurement)
Open AccessArticle
Optimisation of the Transmitter Layout in a VLP System Using an Aperture-Based Receiver
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José Miguel Menéndez and Heidi Steendam
Photonics 2024, 11(6), 517; https://doi.org/10.3390/photonics11060517 - 28 May 2024
Abstract
In this paper, we consider a visible light positioning (VLP) system, where an array of photo diodes combined with apertures is used as a directional receiver and a set of inexpensive and energy-efficient light-emitting diodes (LEDs) is used as transmitters. The paper focuses
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In this paper, we consider a visible light positioning (VLP) system, where an array of photo diodes combined with apertures is used as a directional receiver and a set of inexpensive and energy-efficient light-emitting diodes (LEDs) is used as transmitters. The paper focuses on the optimisation of the layout of the transmitter, i.e., the number and placement of the LEDs, to meet the wanted position estimation accuracy levels. To this end, we evaluate the Cramer–Rao bound (CRB), which is a lower bound on the mean-squared error (MSE) of the position estimate, to analyse the influence of the LEDs’ placement. In contrast to other works, where only the location of the LEDs was considered and/or the optimisation was carried out through simulations, in this work, the optimisation is carried out analytically and considers all the parameters involved in the VLP system as well as the illumination. Based on our results, we formulate simple rules of thumb with which we can determine the spacing between LEDs and the minimum number of LEDs, as well as their position on the ceiling, while also taking into account the requirements for the illumination.
Full article
(This article belongs to the Special Issue Advanced Technologies in Optical Wireless Communications)
Open AccessArticle
Design of Machine Learning-Based Algorithms for Virtualized Diagnostic on SPARC_LAB Accelerator
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Giulia Latini, Enrica Chiadroni, Andrea Mostacci, Valentina Martinelli, Beatrice Serenellini, Gilles Jacopo Silvi and Stefano Pioli
Photonics 2024, 11(6), 516; https://doi.org/10.3390/photonics11060516 - 28 May 2024
Abstract
Machine learning deals with creating algorithms capable of learning from the provided data. These systems have a wide range of applications and can also be a valuable tool for scientific research, which in recent years has been focused on finding new diagnostic techniques
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Machine learning deals with creating algorithms capable of learning from the provided data. These systems have a wide range of applications and can also be a valuable tool for scientific research, which in recent years has been focused on finding new diagnostic techniques for particle accelerator beams. In this context, SPARC_LAB is a facility located at the Frascati National Laboratories of INFN, where the progress of beam diagnostics is one of the main developments of the entire project. With this in mind, we aim to present the design of two neural networks aimed at predicting the spot size of the electron beam of the plasma-based accelerator at SPARC_LAB, which powers an undulator for the generation of an X-ray free electron laser (XFEL). Data-driven algorithms use two different data preprocessing techniques, namely an autoencoder neural network and PCA. With both approaches, the predicted measurements can be obtained with an acceptable margin of error and most importantly without activating the accelerator, thus saving time, even compared to a simulator that can produce the same result but much more slowly. The goal is to lay the groundwork for creating a digital twin of linac and conducting virtualized diagnostics using an innovative approach.
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(This article belongs to the Special Issue Recent Advances in Free Electron Laser Accelerators)
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Open AccessCommunication
Study on the Robustness of an Atmospheric Scattering Model under Single Transmittance
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Xiaotian Shi, Yue Ming, Lin Ju and Shouqian Chen
Photonics 2024, 11(6), 515; https://doi.org/10.3390/photonics11060515 - 28 May 2024
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When light propagates in a scattering medium such as haze, it is partially scattered and absorbed, resulting in a decrease in the intensity of the light emitted by the imaging target and an increase in the intensity of the scattered light. This phenomenon
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When light propagates in a scattering medium such as haze, it is partially scattered and absorbed, resulting in a decrease in the intensity of the light emitted by the imaging target and an increase in the intensity of the scattered light. This phenomenon leads to a significant reduction in the quality of images taken in hazy environments. To describe the physical process of image degradation in haze, the atmospheric scattering model is proposed. However, the accuracy of the model applied to the usual fog image restoration is affected by many factors. In general, fog images, atmospheric light, and haze transmittances vary spatially, which makes it difficult to calculate the influence of the accuracy of parameters in the model on the recovery accuracy. In this paper, the atmospheric scattering model was applied to the restoration of hazed images with a single transmittance. We acquired hazed images with a single transmittance from 0.05 to 1 using indoor experiments. The dehazing stability of the atmospheric scattering model was investigated by adjusting the atmospheric light and transmittance parameters. For each transmittance, the relative recovery accuracy of atmospheric light and transmittance were calculated when they deviated from the optimal value of 0.1, respectively. The maximum parameter estimation deviations allowed us to obtain the best recovery accuracies of 90%, 80%, and 70%.
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Open AccessArticle
Validation of a White Light and Fluorescence Augmented Panoramic Endoscopic Imaging System on a Bimodal Bladder Wall Experimental Model
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Arkadii Moskalev, Nina Kalyagina, Elizaveta Kozlikina, Daniil Kustov, Maxim Loshchenov, Marine Amouroux, Christian Daul and Walter Blondel
Photonics 2024, 11(6), 514; https://doi.org/10.3390/photonics11060514 - 28 May 2024
Abstract
Background: Fluorescence visualization of pathologies, primarily neoplasms in human internal cavities, is one of the most popular forms of diagnostics during endoscopic examination in medical practice. Currently, visualization can be performed in the augmented reality mode, which allows to observe areas of increased
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Background: Fluorescence visualization of pathologies, primarily neoplasms in human internal cavities, is one of the most popular forms of diagnostics during endoscopic examination in medical practice. Currently, visualization can be performed in the augmented reality mode, which allows to observe areas of increased fluorescence directly on top of a usual color image. Another no less informative form of endoscopic visualization in the future can be mapping (creating a mosaic) of the acquired image sequence into a single map covering the area under study. The originality of the present contribution lies in the development of a new 3D bimodal experimental bladder model and its validation as an appropriate phantom for testing the combination of bimodal cystoscopy and image mosaicking. Methods: An original 3D real bladder-based phantom (physical model) including cancer-like fluorescent foci was developed and used to validate the combination of (i) a simultaneous white light and fluorescence cystoscopy imager with augmented reality mode and (ii) an image mosaicking algorithm superimposing both information. Results: Simultaneous registration and real-time visualization of a color image as a reference and a black-and-white fluorescence image with an overlay of the two images was made possible. The panoramic image build allowed to precisely visualize the relative location of the five fluorescent foci along the trajectory of the endoscope tip. Conclusions: The method has broad prospects and opportunities for further developments in bimodal endoscopy instrumentation and automatic image mosaicking.
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(This article belongs to the Special Issue Phototheranostics: Science and Applications)
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High-Power External Spatial Beam Combining of 7-Channel Quantum Cascade Lasers Emitting at ~8.5 μm
by
Haibo Dong, Xuyan Zhou, Man Hu, Yuan Ma, Aiyi Qi, Weiqiao Zhang and Wanhua Zheng
Photonics 2024, 11(6), 513; https://doi.org/10.3390/photonics11060513 - 27 May 2024
Abstract
Based on the demand for high-power output, a spatial beam combining 7-channel quantum cascade lasers (QCLs) is demonstrated in this paper. A “2 + 3 + 2” stepped structure is designed to convert the seven beam spots into a circular arrangement. An aspherical
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Based on the demand for high-power output, a spatial beam combining 7-channel quantum cascade lasers (QCLs) is demonstrated in this paper. A “2 + 3 + 2” stepped structure is designed to convert the seven beam spots into a circular arrangement. An aspherical lens with a large numerical aperture (NA) of 0.85 and a focal length of 1.873 mm is used in each single QCL for collimation, and seven reflectors are utilized in the 7-channel QCLs combined in the spatial beam. After combining the spatial beam, the maximum continuous output power of the system is 3.6 W, and the beam quality M2 is 5.59 in the fast axis and 8.3 in the slow axis, respectively.
Full article
(This article belongs to the Special Issue High Power Lasers: Technology and Applications)
Open AccessArticle
High-Performance NOON State from a Quantum Dot Single Photon for Supersensitive Optical Phase Measurement
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Zhixuan Rao, Jiawei Yang, Luyu Liu and Ying Yu
Photonics 2024, 11(6), 512; https://doi.org/10.3390/photonics11060512 - 27 May 2024
Abstract
We investigate the utilization of advanced single photons produced by quantum dots (QDs) in a microcavity for quantum metrology. Through the integration of lateral excitation and the Purcell effect in an Fabry–Perot microcavity, we realized single-photon emission with an extraction efficiency of 46.39%,
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We investigate the utilization of advanced single photons produced by quantum dots (QDs) in a microcavity for quantum metrology. Through the integration of lateral excitation and the Purcell effect in an Fabry–Perot microcavity, we realized single-photon emission with an extraction efficiency of 46.39%, high purity of 96.91%, and high indistinguishability of 98.32%. Our QD-generated single photons enabled the creation of high-quality NOON states (N = 2) for phase measurement, yielding an interference contrast of 79.79% and surpassing the standard quantum limit (SQL) with phase super-sensitivity. Our results underscore the immense potential of QD-derived single photons for propelling quantum metrology forward, facilitating enhanced precision measurements across diverse applications.
Full article
(This article belongs to the Special Issue Advanced Semiconductor Laser Diodes and Detectors)
Open AccessArticle
The Impact of Pulse Shaping on Coherent Dynamics near a Conical Intersection
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Qici Deng, Junjie Yu, Hongguang Duan and Hongxing He
Photonics 2024, 11(6), 511; https://doi.org/10.3390/photonics11060511 - 27 May 2024
Abstract
Utilizing lasers to probe microscopic physical processes is a crucial tool in contemporary physics research, where the influence of laser properties on excitation processes is a focal point for scientists. In this study, we investigated the impact of laser pulses on the quantum
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Utilizing lasers to probe microscopic physical processes is a crucial tool in contemporary physics research, where the influence of laser properties on excitation processes is a focal point for scientists. In this study, we investigated the impact of laser pulses on the quantum yield of electronic wave packets near conical intersections (CIs). To do so, we employed the time non-local quantum master equation to calculate the time-evolution dynamics of wave packets on excited-state potential energy surfaces (PESs) and projected them onto effective reaction coordinates. The waveform of laser pulses was manipulated by varying the relative amplitude, pulse duration, and center wavelengths of Gaussian profiles. Our calculations revealed that the shape of laser pulses has a discernible impact on the dynamic evolution of electrons in excited states. Furthermore, our research indicated that different pulse profiles exhibit a maximum variation of 6.88% in the quantum yields of electronic wave packets near CIs. Our calculations demonstrate the influence of laser pulse waveform on excitation processes, providing a feasible method for exploring the coherent control of wave packets at conical intersections characterized by strong nonadiabatic coupling.
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(This article belongs to the Special Issue Ultrafast Optics and Applications)
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Open AccessArticle
Research on the Correction Algorithm for Ozone Inversion in Differential Absorption Lidar
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Leyong Li, Chenbo Xie, Jie Ji and Kunming Xing
Photonics 2024, 11(6), 510; https://doi.org/10.3390/photonics11060510 - 27 May 2024
Abstract
Due to the complex and variable nature of the atmospheric conditions, traditional multi-wavelength differential absorption lidar (DIAL) methods often suffer from significant errors when inverting ozone concentrations. As the detection range increases, there is a higher demand for Signal to Noise Ratio (SNR)
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Due to the complex and variable nature of the atmospheric conditions, traditional multi-wavelength differential absorption lidar (DIAL) methods often suffer from significant errors when inverting ozone concentrations. As the detection range increases, there is a higher demand for Signal to Noise Ratio (SNR) in lidar signals. Based on this, the paper discusses the impact of different atmospheric factors on the accuracy of ozone concentration inversion. It also compares the advantages and disadvantages of the two-wavelength differential method and the three-wavelength dual-differential method under both noisy and noise-free conditions. Firstly, the errors caused by air molecular extinction, aerosol extinction, and backscatter terms in the inversion using the two-wavelength differential method were simulated. Secondly, the corrected inversion errors were obtained through direct correction and the introduction of a three-wavelength dual differential correction. Finally, addressing the issue of insufficient SNR in practical inversions, the inversion errors of the two correction methods were simulated by constructing lidar parameters and incorporating appropriate noise. The results indicate that the traditional two-wavelength differential algorithm is significantly affected by aerosols, making it more sensitive to aerosol concentration and structural changes. On the other hand, the three-wavelength dual differential algorithm requires a higher SNR in lidar signals. Therefore, we propose a novel strategy for inverting atmospheric ozone concentration, which prioritizes the use of the three-wavelength dual-differential method in regions with high SNR and high aerosol concentration. Conversely, the direct correction method utilizing the two-wavelength differential approach is used. This approach holds the potential for high-precision ozone concentration profile inversion under different atmospheric conditions.
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(This article belongs to the Special Issue Laser as a Detection: From Spectral Imaging to LiDAR for Remote Sensing Applications)
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Open AccessArticle
Dual-Wavelength Differential Detection of Fiber Bragg Grating Sensors: Towards a Sensor Ecosystem
by
François Ouellette
Photonics 2024, 11(6), 509; https://doi.org/10.3390/photonics11060509 - 27 May 2024
Abstract
We discuss how the dual-wavelength differential detection (DWDD) of fiber Bragg grating sensors can be used to build standardized high-resolution, high-accuracy, large-measurement-range, multichannel instruments and associated sensors. We analyze the system resolution and experimentally show that the high signal-to-noise ratio can allow the
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We discuss how the dual-wavelength differential detection (DWDD) of fiber Bragg grating sensors can be used to build standardized high-resolution, high-accuracy, large-measurement-range, multichannel instruments and associated sensors. We analyze the system resolution and experimentally show that the high signal-to-noise ratio can allow the design of sensors with a ratio of range to resolution superior to 14 bits, and temperature measurement ranges of more than 180 °C. We propose a scheme for real-time signal correction to cancel the drift of the instrument using two internal reference sensors, and a calibration method using centralized golden sensors that allows traceability to international standards for all instruments and sensors, allowing the creation of a global sensor/instrument ecosystem.
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(This article belongs to the Special Issue Optical Fibre Sensing: Recent Advances and Future Perspectives)
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