- 标题
- 摘要
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- 实验方案
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Tunable 50 GHz laser comb generation of multiwavelength Brillouin erbium fiber laser
摘要： We experimentally proposed and widely tunable multiwavelength Brillouin erbium fiber laser (MBEFL) with quintuple Brillouin frequency spacing (~0.4nm, ~50GHz). Only three dispersion compensation fibers spools with total length of 15km as a Brillouin gain media are used. Two sections of an erbium-doped fiber amplifier with maximum pump power of 220mW are utilized. In the developed structure, at port1, we achieved four quintuple Stokes lines of about 10dB peak power and large optical signal to noise ratio of more than 50dB. Wide tuning range of 40nm (1540-1580nm) in the absence of free running modes is recorded using high BP power, BP pre-amplification, and extracting the residual pump power outside the cavity. In addition, another 14 quintuple Stokes channels are produced at another four output ports (port2 to port5). The whole generated 50GHz wavelength spacing signals can be used in dense wavelength division multiplexing communication systems as such large channel spacing can be easily recognized by the optical detector at the receiver terminal.
关键词： Quintuple Brillouin frequency spacing,Tuning range,MBEFL,DWDM
更新于2025-09-23 15:19:57
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Laser-induced breakdown spectroscopy of uranium in the VUV range
摘要： Quantitative analysis of impurities in nuclear materials is necessary in a number of areas, including process control during manufacturing, quality control of products, or for nuclear forensics purposes. Due to the important handling constraints induced by the samples radioactivity and their containment inside airtight enclosures, optical analytical techniques have great advantages over standard ones that require sample preparation, like ICP-based techniques. Therefore, laser-induced breakdown spectroscopy (LIBS) is developed for fast quantitative analysis of impurities in uranium. Actinides are well-known to have a very large number of emission lines in the UV-visible spectral range, hence making the detection of trace or minor elements a real challenge. Therefore, in this study we explored the vacuum ultraviolet range (VUV), i.e. below 200 nm, in order to investigate if this spectral region is more favorable for elemental analysis of uranium by LIBS. As practically no data on VUV spectroscopy of uranium are available, we first analyzed the spectra obtained to assess the spectral density of uranium lines, both in the UV and VUV. Then, the detection limits of two elements, carbon and vanadium, were estimated. It was found that, in spite of a less dense and less intense uranium background in the VUV, this spectral region is not relevant for metal impurities whose spectra are marginally analytically useful in the VUV. Conversely, for non-metals having intense lines in the VUV, the detection limit can be significantly better than in the UV. This was already known for non-nuclear samples. This study extends that conclusion to nuclear materials and has important practical consequences on the implementation of a LIBS analyzer in a nuclear facility.
关键词： vanadium,uranium,Laser-induced breakdown spectroscopy,impurities detection,carbon,VUV range
更新于2025-09-23 15:19:57
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Wide-Angle Polarization-Independent Paratellurite-Based Acousto-Optic Laser Radiation Modulator
摘要： High-efficiency wide-angle polarization-independent acousto-optic diffraction of laser radiation in a paratellurite-based modulator is experimentally studied. The previously published main theoretical principles are confirmed. We have shown that the angular aperture of the acousto-optic modulator can be ~8° in an ultrasonic frequency range of 135–68 MHz depending on the light wavelength and 2°–5° in the range of 20–30 MHz. A wide-angle acousto-optic depolarized laser radiation modulator has been created that operates at a wavelength λ = 1.06 μ m with one output depolarized beam and an efficiency of no less than 90% for input radiation with an angular aperture of 30 mrad.
关键词： light polarization,angular diffraction range,anisotropic acousto-optic diffraction,acousto-optic modulator
更新于2025-09-23 15:19:57
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New Silica Laser-Optimized Multimode Optical Fibers with Extremely Enlarged 100-??m Core Diameter for Gigabit Onboard and Industrial Networks
摘要： We present new type of silica graded index laser-optimized multimode optical fibers (LOMF) with extremely enlarged core diameter up to 100 μm and “typical” “telecommunication” cladding diameter 125 μm. This optical fiber was designed for harsh environment Gigabit onboard cable systems and industrial networks. It differs by special optimized graded refractive index profile, providing low differential mode delay (DMD) for selected guided modes. We present some results of tests, performed for manufactured pilot 520 m length of described LOMF 100/125, concerned with its geometry properties as well as key transmission parameters—attenuation and DMD map.
关键词： mode coupling,laser-based gigabit data transmission,higher-order modes,large core multimode optical fiber,differential mode delay,short-range optical networks,industrial networks,selected guided modes,on-board cable systems,few-mode regime
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Gallium Arsenide Solar Cells Grown on Polycrystalline Germanium Substrates by Aluminum-Induced Crystallization
摘要： Machine-to-machine (M2M) communication represents a new paradigm for mobile cellular networks, where a massive number of low-cost devices request the transfer of small amounts of data without human intervention. One option to tackle this problem is obtained by combining random beamforming (RBF) with opportunistic scheduling. RBF can be used to induce larger channel fluctuations, and opportunistic scheduling can be used to select M2M devices when their overall channel quality is good. Traditional RBF does not fulfill M2M requirements, because overall channel quality needs to be tracked continuously. In order to tackle this limitation, a novel codebook-based RBF architecture that identifies in advance the time instants in which overall channel quality should be reported, within a coherence time window, is proposed. This opportunistic feedback mechanism reduces signaling overhead and enables energy saving at M2M devices. A simplified methodology is presented to evaluate the system mean data rate, using for this purpose closed form formulas derived from SNR distribution approximations. Results reveal that the performance loss that is experienced for introducing the proposed modifications to traditional RBF scheme is negligible. The concepts analyzed in this paper provide useful insights, and show that codebook-based RBF with simplified opportunistic scheduling algorithms is an excellent combination to provide wide-area M2M services with low-cost devices and limited signaling overhead.
关键词： opportunistic scheduling,limited feedback,random beamforming,range extension,Machine-to-machine
更新于2025-09-23 15:19:57
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Improved auto-extrinsic calibration between stereo vision camera and laser range finder
摘要： This study identifies a way to accurately estimate extrinsic calibration parameters between stereo vision camera and 2D laser range finder (LRF) based on 3D reconstruction of monochromatic calibration board and geometric co-planarity constraints between the views from these two sensors. It supports automatic extraction of plane-line correspondences between camera and LRF using monochromatic board, which is further improved by selecting optimal threshold values for laser scan dissection to extract line features from LRF data. Calibration parameters are then obtained by solving co-planarity constraints between the estimated plane and line. Furthermore, the obtained parameters are refined by minimising reprojection error and error from the co-planarity constraints. Moreover, calibration accuracy is achieved because of extraction of reliable plane-line correspondence using monochromatic board which reduces the impact of range-reflectivity-bias observed in LRF data on checkerboard. As the proposed method supports to automatically extract feature correspondences, it provides a major reduction in time required from an operator in comparison to manual methods. The performance is validated by extensive experimentation and simulation, and estimated parameters from the proposed method demonstrate better accuracy than conventional methods.
关键词： plane-line correspondences,laser-camera calibration,Range-reflectivity-bias,automatic feature extraction
更新于2025-09-23 15:19:57
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[IEEE 2019 2nd International Conference on Electrical, Communication, Computer, Power and Control Engineering (ICECCPCE) - Mosul, Iraq (2019.2.13-2019.2.14)] 2019 2nd International Conference on Electrical, Communication, Computer, Power and Control Engineering (ICECCPCE) - Virtual Environment Modelling using Simulated Laser Scanners
摘要： Life quality of people with sever motor disabilities can be improved by developing and inventing new assistive technologies. In this context, it is proposed to develop a semi-autonomous electric wheelchair that has capabilities of navigating through various environments which include different types and sizes of obstacles. This paper describes a methodology to use a range laser scanner mounted on an electric wheelchair to map different environments. The electric wheelchair is simulated in a virtual environment and is developed at the Neurophysiology Laboratory of University of Strathclyde. Mapping the environment is dependent on the information provided by the range laser. An algorithm was developed in MATLAB to record the data received by the range laser and use the data to map the environments and produce a 2D map. The suggested algorithm has been tested using two virtual environments representing rooms with different features. The results showed that range laser scanner can be used on an electric wheelchair platform for efficient mapping of the environment.
关键词： Assistive technologies,Range laser scanner,Virtual environment,Electric wheelchair,Shared control
更新于2025-09-23 15:19:57
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A fluorometric aptasensor for bisphenol a based on the inner filter effect of gold nanoparticles on the fluorescence of nitrogen-doped carbon dots
摘要： An aptamer-based fluorometric assay is described for the determination of bisphenol A (BPA). The aptamer against BPA is first attached to the surface of the red AuNPs, and this prevents the AuNPs from salt-induced formation of a blue-colored aggregate. Hence, the blue fluorescence of added nitrogen-doped carbon dots (NCDots) is quenched via an inner filter effect (IFE) caused by the red AuNPs. After addition of BPA, the BPA/aptamer complex is formed, and the AuNPs are no longer stabilized agains aggregation. This weakens the IFE and results in the recovery of the fluorescence of the NCDots which is measured best at excitation/emission wavelengths of 300/420 nm. The recovered fluorescence increases linearly in the 10 to 250 nM and 250 to 900 nM BPA concentration ranges, and the detection limit is 3.3 nM. The method was successfully applied to the determination of BPA in spiked environmental tap water samples.
关键词： Wide linear range,Quick response,Salt-induced aggregation,Tap water,Low detection limit,BPA/aptamer complexes,Aggregated AuNPs,Environmental-friendly,Fluorescence quenched,Fluorescence recovery
更新于2025-09-23 15:19:57
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A wide dynamic range and high resolution all-fiber-optic turbidity measurement system based on single photon detection technique
摘要： A high-resolution fiber-optic detection system has been developed to measure the wide dynamic range of turbidity. To obtain high-resolution measurement results, a high sensitive single photon detection technique (SPDT) has been used in the system. Based on fiber characteristics, a compact probe structure for fiber-optic integrated transceiver (FITP) is designed to transmitting and collection light signal, which has the capability of detecting turbidity in the narrow workspace. By combining the Beer-Lambert (B-L) law transmission law with single photon counting theory, a novel turbidity measurement theoretical model has been proposed, which shows a good exponential relationship over the whole measurement range from 0.01 to 1000 NTU (Nephelometric Turbidity Units). However, when detecting 0.01–0.1 NTU low turbidity, the experimental results turn into an approximate linear relationship, which good agrees with the proposed theoretical model. Last, some issues about the optimization of light intensity and requiring attention on constructing a practical distributed multi-point water turbidity remote monitoring system in the outdoors are also discussed. It was found that the system can achieve a measurement dynamic range as wide as 50 dB with a resolution better than 0.01 NTU in the range of 0.01–1000 NTU, which is suitable for some specific turbidity measurement in remote and narrow workspace.
关键词： Turbidity measurement,Single photon detection technique,Fiber-optic detection,Wide dynamic range
更新于2025-09-23 15:19:57
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Antenna Range Measurements for Airborne Remote Sensing Antennas
摘要： The DLR Compact Test Range (CTR) is a dual reflector compact range in an electromagnetically shielded chamber for antenna and Radar Cross Section (RCS) measurements under far-field conditions [1]. The quiet zone dimensions allow an evaluation of a volume under test, containing the antenna under test (AUT) in position on the original support structure and surface. Precise in-situ parameters offer extra information about the installed AUT characteristics. These properties are particularly substantial for the radiometric and the polarimetric correction of the propagating signals in imaging microwave sensors, such as Synthetic Aperture Radar (SAR) instruments. F-SAR [2] is a high-resolution multi-frequency fully polarimetric airborne SAR with interferometric capabilities that is developed and operated by the DLR Microwaves and Radar Institute. Spherical swept frequency antenna measurements with continuous moving axis and forward/reverse scanning on offset position AUTs impose specific demands on the analysis. Higher order modes that are present due to test setup and physical constraints are considered in the post-processing. Still, stray signals from the antenna carrying aircraft structure in the proximity contribute to the antenna pattern and remain unfiltered. The particular requirements and status of the applied measurement and processing techniques are described.
关键词： MARS,airborne SAR,Compact Range,SWE,spherical antenna measurement,FFT-Filter
更新于2025-09-23 15:19:57