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Enhanced sensitivity of distributed-temperature sensor with Al-coated fiber based on OFDR
摘要： In this paper, we present a distributed-optical fiber temperature sensor with enhanced sensitivity with Al coating using the Rayleigh backscattering (RBS) spectrum shift measured via optical frequency-domain reflectometry (OFDR). The Al-coated sensing fiber having a larger thermal expansion coefficient than that of silica produces a strain-coupled shift in the RBS under an increase in temperature. This effect leads to an enhanced temperature sensitivity of the distributed measurement scheme. In order to analyze the principle of temperature sensitivity enhancement, a simple analysis was performed by considering the fiber directional strain and force equilibrium between the optical fiber and Al-coated layer. Our results revealed that the temperature sensitivity achieved with the Al-coated fiber in OFDR was ～56% higher relative to that of a single-mode fiber.
关键词： Al-coated fiber,Distributed sensor,Thermal expansion,Optical frequency-domain reflectometry,Temperature sensitivity
更新于2025-09-19 17:15:36
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - The Journey from Manipulating Single Quantum Systems to Quantum Information Processing
摘要： The quality factor of a resonator represents the decay of vibrational energy over time, and is directly related to the frequency response and other key parameters that determine performance of inertial sensors and oscillators. Accurate prediction of the quality factor is essential for designing high-performance microelectromechanical (MEMS) devices. Several to the quality factor. Due to computational complexity, highly simplified models for the dominant dissipation mechanism, such as Zener’s model for thermoelastic dissipation (TED), are often the intuition provided by these models employed. However, is inadequate to predict the quality factor of more complex designs and can be highly misleading. In this paper, we construct complete, quantitative, and predictive models with finite-element methods for the intrinsic energy dissipation mechanisms in MEMS resonators using full anisotropic representation of crystalline silicon and the temperature dependence of all parameters. We find that TED is often a more significant source of damping than has been assumed, because of the previously neglected role of crystalline anisotropy and small geometric features, such as etch release holes—all of which can now be included in practical models. We show that these models, along with simpler scaling models for extrinsic dissipation mechanisms, explain measurements of quality factor in diverse sets of MEMS resonators with unprecedented accuracy.
关键词： internal friction,frequency response,micromechanical resonators,microelectromechanical devices,thermal-mechanical coupling,thermoelastic dissipation,geometry,resonance,systems,Capacitive sensors,damping,energy dissipation,frequency-domain analysis
更新于2025-09-19 17:13:59
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Electro-thermal Model of Approximated Organic Tissue for Investigation of Harmful Electrosurgical Impacts
摘要： The quality factor of a resonator represents the decay of vibrational energy over time, and is directly related to the frequency response and other key parameters that determine performance of inertial sensors and oscillators. Accurate prediction of the quality factor is essential for designing high-performance microelectromechanical (MEMS) devices. Several to the quality factor. Due to computational complexity, highly simplified models for the dominant dissipation mechanism, such as Zener’s model for thermoelastic dissipation (TED), are often the intuition provided by these models employed. However, is inadequate to predict the quality factor of more complex designs and can be highly misleading. In this paper, we construct complete, quantitative, and predictive models with finite-element methods for the intrinsic energy dissipation mechanisms in MEMS resonators using full anisotropic representation of crystalline silicon and the temperature dependence of all parameters. We find that TED is often a more significant source of damping than has been assumed, because of the previously neglected role of crystalline anisotropy and small geometric features, such as etch release holes—all of which can now be included in practical models. We show that these models, along with simpler scaling models for extrinsic dissipation mechanisms, explain measurements of quality factor in diverse sets of MEMS resonators with unprecedented accuracy.
关键词： micromechanical resonators,energy dissipation,Capacitive sensors,frequency-domain analysis,damping,frequency response,geometry,thermal-mechanical coupling,resonance,thermoelastic dissipation,internal friction,microelectromechanical devices,systems
更新于2025-09-19 17:13:59
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Single-input Multiple-output Multi-carrier Wireless Indoor Direction Finding in a Compact Multipath Scenario Using 2.4 GHz ISM Band2
摘要： Super-resolution direction of arrival (DoA) estimation of impinging signals from a line of sight (LOS) source and multiple point scatterers at the 2.4 GHz ISM band is considered within a compact area. The channel is partially frequency ?at in the interested range and all the impinging signals due to the point scatterers are correlated, which introduces the necessity of algorithms for decorrelation of signals. This paper introduces a frequency domain decorrelation scheme for the DoA estimation of a LOS source and point scatterers, which constraints a particular structure on the receiver antenna. The limitation in terms of resolution is demonstrated with respect to the coherence bandwidth of the channel for distinct cases of point scatterer locations with respect to the LOS source.
关键词： coherence bandwidth,line of sight (LOS),2.4 GHz ISM band,direction of arrival (DoA),frequency domain decorrelation
更新于2025-09-19 17:13:59
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[IEEE 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Sarajevo, Bosnia and Herzegovina (2019.9.2-2019.9.4)] 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Time and Memory Complexity of Next-Generation Passive Optical Networks in NS-3
摘要： Single carrier frequency domain equalization (SC-FDE) is an alternative technology to orthogonal frequency division multiplexing to deal with the frequency selective channel fading effect in broadband wireless communication systems. In this paper, we consider a robust SC-FDE design with imperfect channel knowledge at a receiver due to the channel estimation error. Based on a statistical model for channel estimation, the optimal equalization coefficients are derived under the criterion of minimizing the mean square error conditioned on a given channel estimate. The bit error rate is further analyzed and a tight performance approximation is proposed. We also propose two robust FDE schemes in coded systems, where feedback from the channel decoder is utilized to improve the equalization and/or channel estimation performance. Simulation results show that the proposed robust FDE schemes achieve significant performance improvement over the conventional FDE schemes.
关键词： noise predictor,Imperfect channel knowledge,robust frequency domain equalization
更新于2025-09-19 17:13:59
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Combining steady-state with frequency and time domain data to quantitatively analyze charge transport in organic light-emitting diodes
摘要： Typically, organic light-emitting diodes (OLEDs) are characterized only in steady-state to determine and optimize their efficiency. Adding further electro-optical measurement techniques in frequency and time domain helps to analyze charge carrier and exciton dynamics and provides deeper insights into the device physics. We, therefore, first present an overview of frequently used OLED measurement techniques and analytical models. A multilayer OLED with a sky-blue thermally activated delayed fluorescent dopant material is employed in this study without loss of generality. Combining the measurements with a full device simulation allows one to determine specific material parameters such as the charge carrier mobilities of all the layers. The main part of this tutorial focuses on how to systematically fit the measured OLED characteristics with microscopic device simulations based on a charge drift-diffusion and exciton migration model in 1D. Finally, we analyze the correlation and sensitivity of the determined material parameters and use the obtained device model to understand limitations of the specific OLED device.
关键词： charge transport,frequency domain,OLED,time domain,material parameters,device simulation
更新于2025-09-16 10:30:52
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Distributed optical fiber sensing: Review and perspective
摘要： Over the past few decades, optical fibers have been widely deployed to implement various applications in high-speed long-distance telecommunication, optical imaging, ultrafast lasers, and optical sensors. Distributed optical fiber sensors characterized by spatially resolved measurements along a single continuous strand of optical fiber have undergone significant improvements in underlying technologies and application scenarios, representing the highest state of the art in optical sensing. This work is focused on a review of three types of distributed optical fiber sensors which are based on Rayleigh, Brillouin, and Raman scattering, and use various demodulation schemes, including optical time-domain reflectometry, optical frequency-domain reflectometry, and related schemes. Recent developments of various distributed optical fiber sensors to provide simultaneous measurements of multiple parameters are analyzed based on their sensing performance, revealing an inherent trade-off between performance parameters such as sensing range, spatial resolution, and sensing resolution. This review highlights the latest progress in distributed optical fiber sensors with an emphasis on energy applications such as energy infrastructure monitoring, power generation system monitoring, oil and gas pipeline monitoring, and geothermal process monitoring. This review aims to clarify challenges and limitations of distributed optical fiber sensors with the goal of providing a pathway to push the limits in distributed optical fiber sensing for practical applications.
关键词： energy applications,Brillouin scattering,Rayleigh scattering,Raman scattering,optical time-domain reflectometry,distributed optical fiber sensing,optical frequency-domain reflectometry
更新于2025-09-16 10:30:52
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Distributed Fiberoptic Sensor for Simultaneous Humidity and Temperature Monitoring Based on Polyimide-Coated Optical Fibers
摘要： Along temperature, humidity is one of the principal environmental factors that plays an important role in various application areas. Presented work investigates possibility of distributed fiberoptic humidity monitoring based on humidity-induced strain measurement in polyimide (PI)-coated optical fibers. Characterization of relative humidity (RH) and temperature response of four different commercial PI- and one acrylate-coated fiber was performed using optical backscattering reflectometry (OBR). The study addresses issues of temperature-humidity cross-sensitivity, fiber response stability, repeatability, and the influence of annealing. Acrylate-coated fiber exhibited rather unfavorable nonlinear RH response with strong temperature dependence, which makes it unsuitable for humidity sensing applications. On the other hand, humidity response of PI-coated fibers showed good linearity with fiber sensitivity slightly decreasing at rising temperatures. In the tested range, temperature sensitivity of the fibers remained humidity independent. Thermal annealing was shown to considerably improve and stabilize fiber RH response. Based on performed analysis, a 20 m sensor using the optimal PI-coated fibers was proposed and constructed. The sensor uses dual sensing fiber configuration for mutual decoupling and simultaneous measurement of temperature and RH variations. Using OBR, distributed dual temperature-RH monitoring with cm spatial resolution was demonstrated for the first time.
关键词： fiberoptic sensors,distributed humidity sensing,polyimide-coated optical fibers,optical frequency-domain reflectometry,dual sensing
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - A Nonlinear Tuning Compensation Method for OFDR Systems Based on Polynomial Regression Algorithm
摘要： A nonlinear tuning compensation method for optical frequency domain reflection systems based on polynomial regression algorithm is proposed in this paper. Simulation results demonstrate that this method has greatly improved the spatial resolution of measurement.
关键词： Distributed optical fiber sensing,Optical frequency domain reflection,Polynomial regression algorithm,Nonlinear tuning compensation
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE High Power Diode Lasers and Systems Conference (HPD) - Coventry, United Kingdom (2019.10.9-2019.10.10)] 2019 IEEE High Power Diode Lasers and Systems Conference (HPD) - Simulation of the slow-axis beam properties of broad-area lasers and its use in the development of high-brightness sources
摘要： The objective of this work is to demonstrate that the slow-axis beam properties of broad-area diode lasers can be predicted by numerical modeling and that the results guide design decisions in the semiconductor laser development. We present a numerical study for 6 different semiconductor laser single emitter designs and compare the computed results to experimental values. The devices differ in width of the contact opening, cavity length, position and depth of an index trench, and facet re?ectivity.
关键词： Semiconductor Lasers,Index-Guided,Beam Propagation Method,Lasers,Modeling,Gain-Guided,Frequency Domain,Simulation,Thermal Lens,Diode Lasers,Broad-Area
更新于2025-09-16 10:30:52