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
Four-Fold, Cross-Phase Modulation Driven UV Pulse Compression in a Thin Bulk Medium
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
by
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.
Full article
(This article belongs to the Section Lasers, Light Sources and Sensors)
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Open AccessArticle
Compact Single-Shot Dual-Wavelength Interferometry for Large Object Measurement with Rough Surfaces
by
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
by
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
by
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.
Full article
(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
by
Xiaotian Shi, Yue Ming, Lin Ju and Shouqian Chen
Photonics 2024, 11(6), 515; https://doi.org/10.3390/photonics11060515 - 28 May 2024
Abstract
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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
by
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.
Full article
(This article belongs to the Special Issue Phototheranostics: Science and Applications)
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Open AccessCommunication
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
by
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
by
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
by
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.
Full article
(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.
Full article
(This article belongs to the Special Issue Optical Fibre Sensing: Recent Advances and Future Perspectives)
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Open AccessArticle
Gradient Probabilistic Algorithm for Compact Lithium Niobate Integrated Photonic Devices
by
Lizhe Sheng, Haiting Zhang, Jingjing Zhang, Yanqun Tong, Xiaoxian Song, Zijie Dai, Yu Yu, Yanan Wang, Zhongkun Gao, Shuaichen Guan, Kai Guo and Jianquan Yao
Photonics 2024, 11(6), 508; https://doi.org/10.3390/photonics11060508 - 27 May 2024
Abstract
Compact photonic devices are highly desired in photonic integrated circuits. In this work, we use an efficient inverse design method to design a 50/50 beam splitter in lithium niobate integrated platforms. We employ the Gradient Probability Algorithm (GPA), which is built upon traditional
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Compact photonic devices are highly desired in photonic integrated circuits. In this work, we use an efficient inverse design method to design a 50/50 beam splitter in lithium niobate integrated platforms. We employ the Gradient Probability Algorithm (GPA), which is built upon traditional gradient algorithms. The GPA utilizes the adjoint method for the comprehensive calculation of the electric field across the entire design area in a single iteration, thereby deriving the gradient of the design area. This enhancement significantly accelerates the algorithm’s execution speed. The simulation results show that an ultracompact beam splitter with a footprint of m × m can be achieved in lithium niobate integrated platforms, where the insertion loss falls below 0.5 dB within the 1500 nm to 1700 nm range, thus reaching its lowest point of 0.15 dB at 1550 nm.
Full article
(This article belongs to the Special Issue Advanced Photonics Metamaterials and Metasurfaces: Science and Applications)
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The Designed Phase Mask for Suppressing the Inter-Pixel Crosstalk Noise in Intensity-Modulated Multilevel Holographic Data Storage Systems
by
Takuya Nonaka, Soki Hirayama, Tsutomu Shimura and Ryushi Fujimura
Photonics 2024, 11(6), 507; https://doi.org/10.3390/photonics11060507 - 26 May 2024
Abstract
Intensity-modulated signals have the advantage of being directly detectable by the image sensor but have the drawback that the signal quality is easily deteriorated by crosstalk noise, in contrast to phase-modulated signals. In order to suppress the crosstalk noise, we propose a new
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Intensity-modulated signals have the advantage of being directly detectable by the image sensor but have the drawback that the signal quality is easily deteriorated by crosstalk noise, in contrast to phase-modulated signals. In order to suppress the crosstalk noise, we propose a new signal arrangement for multilevel intensity-modulated signals. The concept of our method is to reduce the number of adjacent pixels that are a source of inter-pixel crosstalk noise and to minimize intensity modulation owing to interference with crosstalk noise. We have numerically and experimentally demonstrated that our method can reduce the error rate and improve the recording density compared to the conventional signal arrangement. Our proposed method offers a promising solution for achieving higher recording densities in intensity-modulated holographic data storage systems.
Full article
(This article belongs to the Special Issue Holographic Information Processing)
Open AccessArticle
Interference Mitigation in VLC Systems using a Variable Focus Liquid Lens
by
Krishnendu Bera and Nemai Karmakar
Photonics 2024, 11(6), 506; https://doi.org/10.3390/photonics11060506 - 26 May 2024
Abstract
The field of view (FOV) is an important parameter of a visible light communication (VLC) receiver. A variable FOV can be useful to mitigate interference from neighboring cells in a multi-cell VLC network. The existing works on dynamic FOV VLC receivers have used
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The field of view (FOV) is an important parameter of a visible light communication (VLC) receiver. A variable FOV can be useful to mitigate interference from neighboring cells in a multi-cell VLC network. The existing works on dynamic FOV VLC receivers have used a mechanical iris to control the receiver’s FOV, making the VLC receiver bulky, slow, and power-consuming. In this article, an electronically controlled variable focus liquid lens is used to vary the FOV of the receiver dynamically. A low-cost microcontroller-based feedback control system controls the effective FOV of the receiver to reject signals from unwanted transmitters, thus maximizing the signal-to-interference plus noise ratio (SINR) of the received signal. Experimental results show that the proposed technique effectively improves SINR performance in a multi-cell VLC network. To the best of the authors’ knowledge, this is the first reported work to utilize an electronically controlled compact liquid lens for designing a dynamic FOV VLC receiver.
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(This article belongs to the Special Issue Advanced Technologies in Optical Wireless Communications)
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Refractive Index and Dispersion Measurement Principle with Polarization Change in Total Internal Reflection
by
Jyun-Ping Chang, Cheng-Mu Tsai, Jun-Hong Weng and Pin Han
Photonics 2024, 11(6), 505; https://doi.org/10.3390/photonics11060505 - 25 May 2024
Abstract
Refractive index measurements have been an important task for a long time because that index plays an essential role in describing the optical properties of a material. Many methods have been developed to perform that task. Some of them use interferometry to achieve
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Refractive index measurements have been an important task for a long time because that index plays an essential role in describing the optical properties of a material. Many methods have been developed to perform that task. Some of them use interferometry to achieve high precision. However, these configurations are complicated. Some measure the critical angle using simple structures, but their accuracy is unsatisfactory because it is difficult to judge the exact critical angle with intensity variations. Here, we propose several new schemes based on measuring the polarization change in the total internal reflection. The proposed method has the merits of simple structure and easy incident angle determination that gives the maximum phase change. Additionally, it is possible to find the material dispersion by measuring the wavelength dependence of the polarization ellipticity. Some useful formulas relating the refractive index to the maximum phase change are obtained. This work can provide valuable alternatives for refractive index measurement.
Full article
(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)
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Open AccessArticle
A New Algorithm to Mitigate Fragmentation and Crosstalk in Multi-Core Elastic Optical Networks
by
Jurandir C. Lacerda Jr., Aline G. Morais, Adolfo V. T. Cartaxo and André C. B. Soares
Photonics 2024, 11(6), 504; https://doi.org/10.3390/photonics11060504 - 25 May 2024
Abstract
This paper proposes a core and spectrum allocation algorithm for elastic optical networks based on multi-core fibers. In this context, the fragmentation and crosstalk mitigation algorithm (FraCA) is proposed. FraCA implements mechanisms to reduce spectral fragmentation and inter-core crosstalk in the network, proving
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This paper proposes a core and spectrum allocation algorithm for elastic optical networks based on multi-core fibers. In this context, the fragmentation and crosstalk mitigation algorithm (FraCA) is proposed. FraCA implements mechanisms to reduce spectral fragmentation and inter-core crosstalk in the network, proving efficient when compared with six other algorithms reported in the literature. The numerical results show that when compared with the most competitive of the six algorithms, FraCA achieves a gain of request blocking probability of at least 16.87%, a gain of bandwidth blocking probability of at least 43.95%, and a mean increase in spectral utilization of at least 4.36%.
Full article
(This article belongs to the Special Issue Recent Advances for Next-Generation High-Speed Optical Networks: Technologies, Components, Systems and Architectures)
Open AccessArticle
Ultra-Sensitive Refractive Index Sensing Based on Quasi-BICs in All-Dielectric Nanorod Array
by
Yuefeng Zhao, Zhenghua Wu, Zhihao Feng and Tingyin Ning
Photonics 2024, 11(6), 503; https://doi.org/10.3390/photonics11060503 - 25 May 2024
Abstract
We propose an all-dielectric nanorod array for ultra-sensitive refractive index sensing based on quasi-bound states in the continuum (BICs). The nanorod is fabricated by silicon or silicon with an air hole, i.e., the hollow silicon nanorod. The quasi-BICs are formed in the hollow
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We propose an all-dielectric nanorod array for ultra-sensitive refractive index sensing based on quasi-bound states in the continuum (BICs). The nanorod is fabricated by silicon or silicon with an air hole, i.e., the hollow silicon nanorod. The quasi-BICs are formed in the hollow silicon nanorod array due to the symmetry-breaking of air holes. The high-quality factor (Q-factor) and ultra-narrow reflectance spectral width at quasi-BICs contribute to high performances of the sensor. The numerical results show that the sensitivity and figure of merit (FOM) can reach up to 602.9 nm/RIU and 34,977, respectively. The results indicate that the proposed nanostructures of quasi-BICs are promising for advanced biosensing applications.
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(This article belongs to the Section Lasers, Light Sources and Sensors)
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Open AccessArticle
Air Core ARROW Waveguides Fabricated in a Membrane-Covered Trench
by
Seth Walker, Holger Schmidt and Aaron R. Hawkins
Photonics 2024, 11(6), 502; https://doi.org/10.3390/photonics11060502 - 25 May 2024
Abstract
We report the design, fabrication, and characterization of hollow-core anti-resonant reflecting optical waveguides (ARROWs) fabricated in a membrane-covered trench. These structures are built on silicon wafers using standard microfabrication techniques, including plasma etching, to form trenches. Four waveguide designs are demonstrated, which have
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We report the design, fabrication, and characterization of hollow-core anti-resonant reflecting optical waveguides (ARROWs) fabricated in a membrane-covered trench. These structures are built on silicon wafers using standard microfabrication techniques, including plasma etching, to form trenches. Four waveguide designs are demonstrated, which have different numbers of thin-film reflecting layers. We demonstrate that optical loss decreases with additional reflecting layers, with measured loss coefficients as low as 1 cm−1.
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(This article belongs to the Special Issue Integrated Waveguide-Based Photonic Devices)
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Open AccessArticle
High-Performance Fiber Ring Laser Based on Polarization Space Parity-Time Symmetry Breaking
by
Fengling Zhang, Zhengmao Wu, Xin Tong and Guangqiong Xia
Photonics 2024, 11(6), 501; https://doi.org/10.3390/photonics11060501 - 25 May 2024
Abstract
This work proposes and experimentally demonstrates a high-performance polarization space parity-time (PT) symmetric fiber ring laser to achieve a low-noise, narrow-linewidth, and highly stable single-longitudinal-mode output. The gain/loss and coupling coefficients are regulated by adjusting a polarization controller (PC) and the pumping current
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This work proposes and experimentally demonstrates a high-performance polarization space parity-time (PT) symmetric fiber ring laser to achieve a low-noise, narrow-linewidth, and highly stable single-longitudinal-mode output. The gain/loss and coupling coefficients are regulated by adjusting a polarization controller (PC) and the pumping current of an erbium-doped fiber amplifier (EDFA) within the ring cavity. The results show that the single longitudinal mode oscillation of the laser can be implemented by PT symmetry breaking. The frequency noise spectral density and the linewidth characteristics of the laser are evaluated by the short-delay self-heterodyne method. The results reveal that excellent low-frequency noise (181 Hz2/Hz at a 10 kHz offset frequency) and narrow fundamental linewidth (68 Hz) can be achieved. Additionally, the laser exhibits outstanding stability with only 0.64 pm wavelength drift over 30 min. By tuning an optical tunable filter (OTF), the wavelength tunable range of the laser can cover the entire C-band. Furthermore, the impacts of different fiber length on the frequency noise spectral density and the filter bandwidth on stability are analyzed, offering guidance for component selection in such laser systems.
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(This article belongs to the Special Issue Advanced Lasers and Their Applications II)
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