Optics Communications最新文献

{"title":"Photonic reservoir computing for parallel task processing based on a feedback-free spin-polarized VCSEL","authors":"Yigong Yang,&nbsp;Yu Huang,&nbsp;Pei Zhou,&nbsp;Nianqiang Li","doi":"10.1016/j.optcom.2024.131225","DOIUrl":"10.1016/j.optcom.2024.131225","url":null,"abstract":"<div><div>Time delayed reservoir computing (RC) is a novel artificial neural network that is easy to implement in hardware due to its extremely simple structure. Because of its time-division multiplexed information processing, laser-based photonic time-delayed RCs usually realize parallel processing with polarization/wavelength multiplexing. However, the performance of two different tasks is difficult to regulate separately and simultaneously in the time delayed RC system, especially for the chip-scale configuration. Here, we propose a feedback-free RC system based on a spin-polarized vertical-cavity surface-emitting semiconductor laser (VCSEL), which simplifies the whole system structure and can process time series prediction and waveform recognition tasks in parallel, with employing the input and output coding to provide the effect from past states. By separately setting the number of past states introduced by the coding for the two tasks, the performance of the two tasks can be adjusted respectively. Furthermore, by appropriately tuning the pump polarization ellipticity which is the unique feature for the spin-polarized VCSEL, the computational ability of the proposed RC can be focused on one of the two parallel tasks. Therefore, the proposed RC system is capable of dealing with different tasks with high performance, and also expected to provide a viable solution for integrated neuromorphic computing systems due to its compact, feedback-free structure.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131225"},"PeriodicalIF":2.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrasensitive strain sensor of dual parallel FPIs utilizing femtosecond laser processing and Vernier effect","authors":"Changli Dong,&nbsp;Changning Liu","doi":"10.1016/j.optcom.2024.131210","DOIUrl":"10.1016/j.optcom.2024.131210","url":null,"abstract":"<div><div>This study proposes and develops a highly sensitive fiber optic strain sensor utilizing femtosecond laser processing and the Vernier effect. The sensor features two parallel Fabry-Pérot interferometers (FPI), with each FPI consisting of an air bubble and a tapered fiber optic cascade. FPI 2 serves as the sensing cavity, while FPI 1 acts as the reference cavity. The strain sensing capability of a single FPI 2 is measured at 6.67 p.m./με, while the parallel configuration of FPI 2 with FPI 1 achieves a sensitivity of 68.3 p.m./με, resulting in an amplification of 10.24. Furthermore, the proposed sensor demonstrates excellent repeatability, low-temperature cross-sensitivity, simple fabrication, and cost-effectiveness, making it a promising tool for strain measurement applications.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131210"},"PeriodicalIF":2.2,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A TDLAS gas detection method based on digital signal modulation","authors":"Lei Zhang,&nbsp;Xin Dai,&nbsp;Weihua Zhang,&nbsp;Wenqing Wang,&nbsp;Xiaochen Liu,&nbsp;Wenbo Li","doi":"10.1016/j.optcom.2024.131211","DOIUrl":"10.1016/j.optcom.2024.131211","url":null,"abstract":"<div><div>This research presents a novel TDLAS gas concentration detection method based on digital modulation. The method inherits the advantage of a simple system structure from Direct Absorption Spectroscopy, as well as the excellent sensitivity of Wavelength Modulation Spectroscopy. A low-frequency sawtooth wave is employed to drive the laser, resulting in a digital direct absorption spectrum signal. By constructing a cosine modulation sequence in the time domain and performing linear interpolation on the direct absorption spectrum, it successfully converts to a wavelength-modulated absorption spectrum and simultaneously generates a digital reference signal at double the frequency. Ultimately, phase-locked amplification technology can be used to calculate the amplitude of the second harmonic. Since both the modulation and reference signals are generated digitally, they ensure a strict frequency-doubling relationship and phase correlation, which not only reduces the complexity of the hardware system but also effectively minimizes system errors. Because digital technology generates both the modulation and reference signals, it ensures that they have the same phase and a strict frequency-doubling relationship. Experimental results demonstrate that, when fitted by a cubic polynomial, the second harmonic amplitude and the gas concentration have a correlation coefficient (R²) as high as 0.99999 and a root mean square error as low as 0.0011. This proves the method's great accuracy and reliability in practical applications.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131211"},"PeriodicalIF":2.2,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Suppression of interference fringes in wavelength modulation spectroscopy based on convolutional neural networks","authors":"Wenke Liang,&nbsp;Mingshan Yao","doi":"10.1016/j.optcom.2024.131201","DOIUrl":"10.1016/j.optcom.2024.131201","url":null,"abstract":"<div><div>To mitigate interference fringes in wavelength modulated spectroscopy (WMS), we introduce a new filter based on convolutional neural networks (New CNNF). This filter effectively suppresses both high and low-frequency variations of interference fringes, including those with envelopes. In striving for comprehensive interference fringe suppression across the entire frequency spectrum, while accommodating diverse cavity length conditions, we confront the challenge of data sparsity. To address this, we introduce a pioneering methodology: finely segmenting the dataset through concentration column density normalization, thereby achieving notable noise reduction. Through the construction and training of the New CNNF model, it was found to exhibit superior performance compared to traditional filtering algorithms, particularly under low signal-to-noise ratio (SNR) conditions.</div><div>Following processing with the novel convolutional neural network filters (New CNNF), the sample's signal-to-noise ratio (SNR) improved by 26.70 dB, increasing from the original −10.11 dB. When the etalon lengths were 2 cm and 100 cm, the goodness of fit between the predicted second harmonic signal amplitude by New CNNF and the corresponding label concentration reached 0.9995 and 0.9999, respectively. Experimental results demonstrate that New CNNF effectively suppresses high and low-frequency variations and enveloped interference fringes in the TDLAS-WMS system, thereby enhancing the accuracy and stability of methane concentration measurements. CH4 transitions at λ = 1.654 μm were selected to validate this approach. Our method shows promising application prospects and can be extended to the sensing of other gas molecules.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131201"},"PeriodicalIF":2.2,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Q coupled topological edge state in 1D photonic crystal mirror heterostructure for ultrasensitive thermal sensing","authors":"Yassine Bouazzi ,&nbsp;Mohamed Saleh M. Esmail ,&nbsp;Mabrouk Touahmia ,&nbsp;Ayyaz Ahmad ,&nbsp;Sayed El. Soliman","doi":"10.1016/j.optcom.2024.131198","DOIUrl":"10.1016/j.optcom.2024.131198","url":null,"abstract":"<div><div>This work explores a novel 1D topological photonic crystal (PC) mirror heterostructure for high-performance thermal sensing. The design leverages a unique coupled topological edge state mode (CTES) exhibiting exceptional light confinement at the interface, characterized by a record-high quality (<span><math><mrow><mi>Q</mi></mrow></math></span>) factor. The study investigates the effects of nematic liquid crystal (NLC) integration and temperature variations to enhance functionality. Two NLC defect configurations are explored: complete replacement of silica layers and localized replacement within one topological PC. In both scenarios, the CTES mode exhibits tunability in frequency and <span><math><mrow><mi>Q</mi></mrow></math></span> factor due to the thermo-optic properties of the NLC. This dynamic control offers advantages for various applications beyond thermal sensing, including filtering and switching. The first NLC configuration achieves an outstanding <span><math><mrow><mi>Q</mi></mrow></math></span> factor of <span><math><mrow><msup><mn>10</mn><mn>7</mn></msup></mrow></math></span>, surpassing the intrinsic value. Additionally, it demonstrates exceptional thermal sensitivity (−0.12317 nm/°C) and a remarkable figure of merit (1002.48 <span><math><mrow><msup><mrow><mo>°</mo><mi>C</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>). These superior sensing characteristics are attributed to the strong light localization at the interface and the intensified light-matter interaction facilitated by the NLC. The second configuration offers a trade-off between sensitivity and tunability, exhibiting a <span><math><mrow><mi>Q</mi></mrow></math></span> factor in the <span><math><mrow><msup><mn>10</mn><mn>6</mn></msup></mrow></math></span> range, a sensitivity of −0.05853 nm/°C, and a figure of merit of 86.53 <span><math><mrow><msup><mrow><mo>°</mo><mi>C</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>. This study presents a groundbreaking design for 1D topological PC mirror heterostructures with integrated NLC. This platform holds immense promise for developing high-performance, tunable narrowband filters and ultrasensitive thermal sensors, paving the way for advancements in diverse photonic applications.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131198"},"PeriodicalIF":2.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of femtosecond fiber lasers in technology and science","authors":"Martin E. Fermann ,&nbsp;Antoine Rolland","doi":"10.1016/j.optcom.2024.131197","DOIUrl":"10.1016/j.optcom.2024.131197","url":null,"abstract":"<div><div>We present a first-hand view of the early origins of femtosecond fiber technology built upon the foundations of ultrafast optics established in the sixties, seventies, and eighties. We discuss what considerations led to the establishment of early femtosecond oscillator designs and how they have been improved over the years. Another aspect of this article deals with the road to ever increasing pulse energies and average powers that can be achieved based on various amplification techniques. We go on to review the journey toward achieving greater precision enabled via the invention of frequency combs and the incorporation of frequency comb technology within the realm of fiber optics. The paper concludes with a brief overview of some of the most important fiber laser applications and provides a preview of what may lie ahead in the future.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131197"},"PeriodicalIF":2.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Terahertz branching waveguide coupler with tunable coupling degree based on vanadium dioxide","authors":"Wu Pan ,&nbsp;Sen Qiu ,&nbsp;Zhen Zhang ,&nbsp;Kuan Ye ,&nbsp;Lei Huang ,&nbsp;Renpu Li","doi":"10.1016/j.optcom.2024.131196","DOIUrl":"10.1016/j.optcom.2024.131196","url":null,"abstract":"<div><div>This paper presents a terahertz branch waveguide directional coupler with tunable coupling based on vanadium dioxide (VO₂). Tuning of the coupling degree can be realized by the VO₂ film covering the surface of the branch waveguide. The tuning range of the coupling degree depended on the total width of the branch waveguide and the width of the branch encompassed by the VO₂ film. The coupling degree can be adjusted by controlling the conductivity of the VO₂ film. The operating frequency of the coupler was approximately 220 GHz, and the tuning range was from 3 dB to 20 dB. The isolation and return losses of the coupler were less than 20 dB. This coupler can realize coupling tuning and has potential applications in the field of terahertz communication.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131196"},"PeriodicalIF":2.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fabrication of grooves on 4H–SiC using femtosecond laser vector beam","authors":"Jia-Fan Kuo ,&nbsp;Chung-Wei Cheng","doi":"10.1016/j.optcom.2024.131200","DOIUrl":"10.1016/j.optcom.2024.131200","url":null,"abstract":"<div><div>Femtosecond lasers are widely acknowledged for their capability to groove and generate laser-induced periodic surface structures (LIPSS) on various materials. LIPSS structures include LSFL (low spatial frequency LIPSS) and HSFL (high spatial frequency LIPSS). In this study, a segmented waveplate (SWP) was used to transform a linearly polarized femtosecond laser Gaussian beam with a wavelength of 515 nm into a vector beam with a donut-shaped energy peak distribution and polarization of azimuthal and radial. Grooving was conducted on three different SiC surface conditions: polished and pre-processed (LSFL and HSFL), using linear, azimuthal, and radial polarization. This study investigated the differences in microstructure morphology and compared the ablation depths of the grooves. It was found that grooving on pre-processed LSFL 4H–SiC surfaces resulted in grooves with higher ablation depths than those produced on polished surfaces. Additionally, using azimuthal polarization on the HSFL surface could create fine HSFL structures (with a period of approximately 100 nm) between the initial periodic structures (with a period of approximately 250 nm) formed during the pre-processing.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131200"},"PeriodicalIF":2.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling and application of array light sources in ultraviolet communication systems","authors":"Jiachen Liu,&nbsp;Taifei Zhao,&nbsp;Ziyao Gao,&nbsp;Hui Li","doi":"10.1016/j.optcom.2024.131190","DOIUrl":"10.1016/j.optcom.2024.131190","url":null,"abstract":"<div><div>Reliable communication over long distances using ultraviolet (UV) light is challenging due to the strong scattering and atmospheric absorption of UV light. However, with advancements in UV LED technology, the performance of transmitters can be significantly enhanced by employing an array of light sources, which improves the overall quality of communication. Despite these advancements, the impact of various array configurations — such as shape, quantities, and other parameters — on light intensity distribution and UV optical communication remains largely unexplored. In this work, we first modeled the light intensity distribution of arrayed light sources with varying shapes, quantities, and other parameters. We improved the traditional Monte Carlo method to better accommodate these distributions, enabling more accurate simulations. Subsequently, we obtained simulation results for different array configurations. Building on these findings, we developed a UV LED array communication system that achieved a bit error rate (BER) of <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> for information transmission over a distance of 500 m. This research provides valuable insights into the long-distance transmission capabilities of UV light using arrayed light sources.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131190"},"PeriodicalIF":2.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reliability and security performances analysis of rate splitting based VLC system with HARQ","authors":"Wei Guo ,&nbsp;Yanzhe Sun ,&nbsp;Ping Wang ,&nbsp;Shiceng Zhang ,&nbsp;Ting Yang ,&nbsp;Zifan Li ,&nbsp;Qi Liu ,&nbsp;Bo Bai","doi":"10.1016/j.optcom.2024.131199","DOIUrl":"10.1016/j.optcom.2024.131199","url":null,"abstract":"<div><div>This work first attempts to investigate the reliability and physical layer security (PLS) performances of a rate splitting (RS) based visible light communication (VLC) system with one trusted user and one untrusted user. Specifically, the hybrid automatic repeat request (HARQ) protocol is adopted at the trusted user and the movement of users is assumed to be subject to the random way point (RWP) model with four decoding strategies considered at receiver side. The exact closed-form expressions of outage probability (OP) for both users are then obtained, and the analytical expressions of secrecy outage probability (SOP), reliable and secure transmission probability (RSP), and effective secrecy throughput (EST) of trusted user are also mathematically derived. Through simulations, it is found that to guarantee the reliability and PLS performances, the trusted user should first decode the untrusted user's private stream and the untrusted user should first decode the trusted user's private stream. Besides, the reliability and PLS performances of RS-VLC system could be enhanced with the appropriate increase in the maximum transmission round of HARQ with the best decoding strategy. Moreover, they could be further enhanced by the proper common stream power allocation coefficient. This work will benefit the research and development of indoor VLC system.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"574 ","pages":"Article 131199"},"PeriodicalIF":2.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}