Optics Communications最新文献_第9页

Photonic reservoir computing for parallel task processing based on a feedback-free spin-polarized VCSEL 基于无反馈自旋极化 VCSEL 的用于并行任务处理的光子存储计算

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-16 DOI: 10.1016/j.optcom.2024.131225

Yigong Yang, Yu Huang, Pei Zhou, Nianqiang Li

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.

延时存储计算（RC）是一种新型人工神经网络，由于其结构极其简单，因此很容易在硬件中实现。由于具有时分复用信息处理功能，基于激光的光子延时 RC 通常可以实现偏振/波长复用的并行处理。然而，在延时 RC 系统中，很难同时单独调节两种不同任务的性能，尤其是在芯片级配置中。在此，我们提出了一种基于自旋偏振垂直腔表面发射半导体激光器（VCSEL）的无反馈 RC 系统，它简化了整个系统的结构，可以并行处理时间序列预测和波形识别任务，并利用输入和输出编码提供过去状态的效果。通过分别设置两个任务的编码所引入的过去状态的数量，可以分别调整两个任务的性能。此外，通过适当调整泵浦偏振椭圆度（这是自旋偏振 VCSEL 的独有特征），可以将拟议 RC 的计算能力集中于两个并行任务中的一个。因此，所提出的 RC 系统能够高性能地处理不同的任务，而且由于其结构紧凑、无反馈，有望为集成神经形态计算系统提供可行的解决方案。

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引用次数: 0

Ultrasensitive strain sensor of dual parallel FPIs utilizing femtosecond laser processing and Vernier effect 利用飞秒激光加工和游标效应的双平行 FPI 超灵敏应变传感器

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-15 DOI: 10.1016/j.optcom.2024.131210

Changli Dong, Changning Liu

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.

本研究提出并开发了一种利用飞秒激光加工和维尼尔效应的高灵敏光纤应变传感器。该传感器具有两个平行的法布里-佩罗干涉仪（FPI），每个 FPI 由一个气泡和一个锥形光纤级联组成。FPI 2 作为传感腔，而 FPI 1 作为参考腔。据测量，单个 FPI 2 的应变传感能力为 6.67 p.m./με ，而 FPI 2 与 FPI 1 并联配置的灵敏度为 68.3 p.m./με ，放大倍数为 10.24。此外，所提出的传感器还具有出色的重复性、低温交叉灵敏度、制造简单和成本效益高的特点，使其成为应变测量应用中一种前景广阔的工具。

引用次数: 0

A TDLAS gas detection method based on digital signal modulation 基于数字信号调制的 TDLAS 气体检测方法

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-15 DOI: 10.1016/j.optcom.2024.131211

Lei Zhang, Xin Dai, Weihua Zhang, Wenqing Wang, Xiaochen Liu, Wenbo Li

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.

本研究提出了一种基于数字调制的新型 TDLAS 气体浓度检测方法。该方法继承了直接吸收光谱法系统结构简单的优点和波长调制光谱法灵敏度高的特点。利用低频锯齿波驱动激光，产生数字直接吸收光谱信号。通过在时域中构建余弦调制序列并对直接吸收光谱进行线性插值，它可以成功转换为波长调制吸收光谱，并同时生成频率为两倍的数字参考信号。最终，锁相放大技术可用于计算二次谐波的振幅。由于调制信号和参考信号都是数字生成的，因此它们能确保严格的倍频关系和相位相关性，这不仅降低了硬件系统的复杂性，还能有效减少系统误差。由于调制信号和参考信号均由数字技术生成，因此可以确保它们具有相同的相位和严格的倍频关系。实验结果表明，用三次多项式拟合时，二次谐波振幅与气体浓度的相关系数（R2）高达 0.99999，均方根误差低至 0.0011。这证明该方法在实际应用中非常准确可靠。

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引用次数: 0

Suppression of interference fringes in wavelength modulation spectroscopy based on convolutional neural networks 基于卷积神经网络抑制波长调制光谱学中的干涉条纹

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-14 DOI: 10.1016/j.optcom.2024.131201

Wenke Liang, Mingshan Yao

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.

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.

为了减轻波长调制光谱（WMS）中的干涉条纹，我们引入了一种基于卷积神经网络的新型滤波器（New CNNF）。这种滤波器能有效抑制干扰条纹的高频和低频变化，包括那些带包络线的干扰条纹。为了在整个频谱范围内全面抑制干涉条纹，同时适应不同的腔长条件，我们面临着数据稀疏性的挑战。为此，我们引入了一种开创性的方法：通过浓度柱密度归一化对数据集进行精细分割，从而实现显著的降噪。通过新型卷积神经网络过滤器（New CNNF）的处理，样本的信噪比（SNR）从原来的-10.11 dB提高了26.70 dB。当蚀刻管长度为 2 厘米和 100 厘米时，新 CNNF 预测的二次谐波信号振幅与相应标签浓度的拟合度分别达到 0.9995 和 0.9999。实验结果表明，新 CNNF 有效抑制了 TDLAS-WMS 系统中的高低频变化和包络干涉条纹，从而提高了甲烷浓度测量的准确性和稳定性。我们选择了 λ = 1.654 μm 处的 CH4 转变来验证这种方法。我们的方法显示出广阔的应用前景，并可扩展到其他气体分子的传感。

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引用次数: 0

High-Q coupled topological edge state in 1D photonic crystal mirror heterostructure for ultrasensitive thermal sensing 用于超灵敏热感应的一维光子晶体镜面异质结构中的高 Q 值耦合拓扑边缘态

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-11 DOI: 10.1016/j.optcom.2024.131198

Yassine Bouazzi , Mohamed Saleh M. Esmail , Mabrouk Touahmia , Ayyaz Ahmad , Sayed El. Soliman

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 (

Q

) 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

Q

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

Q

factor of

10^{7}

, surpassing the intrinsic value. Additionally, it demonstrates exceptional thermal sensitivity (−0.12317 nm/°C) and a remarkable figure of merit (1002.48

{° C}^{- 1}

). 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

Q

factor in the

10^{6}

range, a sensitivity of −0.05853 nm/°C, and a figure of merit of 86.53

{° C}^{- 1}

. 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.

这项研究探索了一种用于高性能热传感的新型一维拓扑光子晶体（PC）镜面异质结构。该设计利用独特的耦合拓扑边缘态模式 (CTES)，在界面上表现出卓越的光局限性，并以创纪录的高品质因数 (Q) 为特征。研究调查了向列液晶 (NLC) 集成和温度变化对增强功能的影响。研究探讨了两种 NLC 缺陷配置：硅层的完全置换和一个拓扑 PC 内的局部置换。在这两种情况下，由于 NLC 的热光学特性，CTES 模式都表现出频率和 Q 因数的可调性。这种动态控制为热感应以外的各种应用提供了优势，包括滤波和开关。第一种 NLC 配置实现了 107 的出色 Q 因子，超过了固有值。此外，它还表现出卓越的热灵敏度（-0.12317 nm/°C）和显著的优点系数（1002.48 °C-1）。这些卓越的传感特性归功于界面上的强光定位以及 NLC 所促进的光-物质相互作用的增强。第二种配置在灵敏度和可调性之间进行了权衡，其 Q 值在 106 范围内，灵敏度为 -0.05853 nm/°C，优点系数为 86.53 °C-1。这项研究提出了集成 NLC 的一维拓扑 PC 镜异质结构的突破性设计。这一平台为开发高性能、可调谐窄带滤波器和超灵敏热传感器带来了巨大前景，为各种光子应用的进步铺平了道路。

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引用次数: 0

The impact of femtosecond fiber lasers in technology and science 飞秒光纤激光器对技术和科学的影响

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-11 DOI: 10.1016/j.optcom.2024.131197

Martin E. Fermann , Antoine Rolland

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.

我们以第一手资料介绍了飞秒光纤技术的早期起源，该技术建立在六十年代、七十年代和八十年代建立的超快光学基础之上。我们讨论了早期飞秒振荡器设计的形成原因，以及多年来如何对其进行改进。本文的另一个主题是基于各种放大技术不断提高脉冲能量和平均功率。我们接着回顾了通过发明频率梳和将频率梳技术融入光纤领域实现更高精度的历程。最后，本文简要概述了一些最重要的光纤激光应用，并对未来的发展进行了展望。

引用次数: 0

Terahertz branching waveguide coupler with tunable coupling degree based on vanadium dioxide 基于二氧化钒的具有可调耦合度的太赫兹分支波导耦合器

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-11 DOI: 10.1016/j.optcom.2024.131196

Wu Pan , Sen Qiu , Zhen Zhang , Kuan Ye , Lei Huang , Renpu Li

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.

本文介绍了一种基于二氧化钒（VO2）的具有可调耦合度的太赫兹分支波导定向耦合器。耦合度的调谐可通过覆盖在分支波导表面的二氧化钒薄膜来实现。耦合度的调节范围取决于分支波导的总宽度和 VO2 薄膜覆盖的分支宽度。耦合度可以通过控制 VO2 薄膜的电导率来调节。耦合器的工作频率约为 220 GHz，调谐范围为 3 dB 至 20 dB。耦合器的隔离度和回波损耗均小于 20 dB。这种耦合器可以实现耦合调谐，在太赫兹通信领域具有潜在的应用前景。

引用次数: 0

Fabrication of grooves on 4H–SiC using femtosecond laser vector beam 利用飞秒激光矢量束在 4H-SiC 上制作凹槽

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-11 DOI: 10.1016/j.optcom.2024.131200

Jia-Fan Kuo , Chung-Wei Cheng

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.

飞秒激光在各种材料上开槽和生成激光诱导周期性表面结构（LIPSS）的能力已得到广泛认可。LIPSS 结构包括 LSFL（低空间频率 LIPSS）和 HSFL（高空间频率 LIPSS）。在这项研究中，使用分段波板（SWP）将波长为 515 nm 的线性偏振飞秒激光高斯光束转化为具有甜甜圈形能量峰分布以及方位和径向偏振的矢量光束。在三种不同的碳化硅表面条件（抛光和预处理（LSFL 和 HSFL））下，使用线性、方位和径向偏振进行开槽。这项研究调查了微观结构形态的差异，并比较了沟槽的烧蚀深度。研究发现，与抛光表面相比，在预处理的 LSFL 4H-SiC 表面开槽产生的沟槽烧蚀深度更高。此外，在 HSFL 表面使用方位偏振可以在预处理期间形成的初始周期性结构（周期约为 250 nm）之间形成精细的 HSFL 结构（周期约为 100 nm）。

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引用次数: 0

Modeling and application of array light sources in ultraviolet communication systems 紫外线通信系统中阵列光源的建模与应用

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-11 DOI: 10.1016/j.optcom.2024.131190

Jiachen Liu, Taifei Zhao, Ziyao Gao, Hui Li

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

1 0^{- 6}

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.

由于紫外光具有强烈的散射和大气吸收，因此使用紫外光进行远距离可靠通信具有挑战性。不过，随着紫外线 LED 技术的进步，发射器的性能可以通过采用光源阵列得到显著提高，从而改善整体通信质量。尽管取得了这些进步，但各种阵列配置（如形状、数量和其他参数）对光强分布和紫外光通信的影响在很大程度上仍未得到探讨。在这项工作中，我们首先模拟了具有不同形状、数量和其他参数的阵列光源的光强分布。我们改进了传统的蒙特卡罗方法，以更好地适应这些分布，从而实现更精确的模拟。随后，我们获得了不同阵列配置的模拟结果。在这些研究成果的基础上，我们开发出了紫外 LED 阵列通信系统，该系统在 500 米距离内的信息传输误码率 (BER) 为 10-6。

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引用次数: 0

Reliability and security performances analysis of rate splitting based VLC system with HARQ 基于速率分割和 HARQ 的 VLC 系统的可靠性和安全性分析

IF 2.2 3区物理与天体物理 Q2 OPTICS

Optics Communications

Pub Date : 2024-10-11 DOI: 10.1016/j.optcom.2024.131199

Wei Guo , Yanzhe Sun , Ping Wang , Shiceng Zhang , Ting Yang , Zifan Li , Qi Liu , Bo Bai

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.

本研究首次尝试研究基于速率分裂（RS）的可见光通信（VLC）系统的可靠性和物理层安全性（PLS）性能，该系统有一个可信用户和一个不可信用户。具体来说，受信任用户采用混合自动重复请求（HARQ）协议，用户的移动被假定为随机路点（RWP）模型，接收端考虑了四种解码策略。然后得到两个用户的中断概率（OP）的精确闭式表达式，并用数学方法推导出可信用户的保密中断概率（SOP）、可靠安全传输概率（RSP）和有效保密吞吐量（EST）的解析表达式。通过仿真发现，要保证可靠性和 PLS 性能，可信用户应首先解码不可信用户的私有数据流，不可信用户应首先解码可信用户的私有数据流。此外，在采用最佳解码策略的情况下，适当增加 HARQ 的最大传输轮数，可以提高 RS-VLC 系统的可靠性和 PLS 性能。此外，适当的公共流功率分配系数也能进一步提高可靠性和 PLS 性能。这项工作将有利于室内 VLC 系统的研究和开发。

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引用次数: 0