- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Multi-aperture fiber coherent combining system in urban horizontal atmospheric laser link
摘要： Multi-aperture receiver with optical combining architecture is an effective approach to overcome the turbulent atmosphere effect on the performance of the free-space optical (FSO) communications. In this paper, we built a 1 km urban horizontal link, and adopted beam combining system with four apertures at receiver. By analogy with aperture smoothing factor, we proposed the concept of fluctuation suppression ratio to evaluate the mitigation ability of the system on atmospheric fading. The experimental results confirmed that the beam combining system can perform best when the aperture interval is larger than the coherent length, and the performance decreases with the increase of the coherent length. Moreover, we found that the change of phase differences between the input beams is more than 40 ??rad, which provides reference for future system design.
关键词： Scintillation index,Atmospheric turbulence,Multi-aperture,Optical coherent combining
更新于2025-09-19 17:13:59
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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) - Measurement Uncertainties in the Calibration of Multi-Junction Solar Cells using Different Sun Simulators and Reference Devices
摘要： The CMS lead tungstate (PbWO4) electromagnetic calorimeter (ECAL) has successfully achieved its first goal: the discovery of the Higgs boson in 2012. However, longevity studies show that part of the PbWO4 ECAL will not maintain the required performance due to radiation damage incurred at the HL-LHC. The forward region of the detector will suffer the most from radiation damage, and the ECAL Endcaps (EE) will need to be replaced. A scintillator-based option for the EE replacement, Shashlik EE, is presented in the paper. The Shashlik EE is a sampling calorimeter. Tungsten absorber plates are interleaved with scintillator plates (LYSO or CeF3), with quartz and wavelength-shifting (WLS) capillaries optically coupled to the scintillator plates for light output. The Shashlik EE maintains an excellent energy resolution, but compared to the current PbWO4 EE, it is at least five times greater in radiation hardness and has a module size four times smaller allowing four times higher granularity laterally for pileup mitigation and particle identification. Irradiation tests and beam tests results have confirmed the high performance of the Shashlik EE.
关键词： Calorimetry,solid scintillation detectors,photondetectors
更新于2025-09-19 17:13:59
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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) - Sandwich in the Middle: Enhancing the Optomechanical Coupling
摘要： This paper is the fifth in a series of articles on the basic physics of light yield nonproportionality in scintillators. Here, we compare and contrast the nonproportionality as registered by gamma rays and high-energy electrons. As has been noted in the past, these two types of data have different curve shapes (for plots of the light yield against electron or gamma energy). Herein, we show how the experimental gamma nonproportionality curve can be calculated from the electron response by accounting for the distribution of high energy electrons created by the gamma photon via the photoelectric interaction. Similarly, we measure and model the gamma-induced resolution as a function of energy and compare this data to predictions from our model. The utility of the model is explored using data acquired with the scintillators (Eu), GYGAG(Ce) and CsI(Na).
关键词： Gamma ray detectors,luminescence,solid scintillation detectors
更新于2025-09-19 17:13:59
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Turbulence and Related Phenomena || The Turbulence Regime of the Atmospheric Surface Layer in the Presence of Shallow Cold Drainage Flows: Application of Laser Scintillometry
摘要： The presence of shallow cold flows in the atmospheric boundary layer (ABL) instigates changes in the turbulent regime of the atmospheric surface layer (ASL). This small scale flow circulation introduces radiative cooling controls over large areas in polar latitudes during winter. In this study, microscale dynamic and turbulent variables have been obtained in the framework of the Winter Boundary Layer Experiment in Fairbanks, Alaska, developed during the winters of 2009/2010 and 2010/2011. Multiscale surface turbulence observations based on Eddy covariance and laser scintillometry were combined with Doppler acoustic sounding to document simultaneous changes in the ABL flow and ASL turbulence. We computed changes in momentum and heat fluxes characterizing intermittent and persistent modes of the drainage flow over three study cases. On the basis of laser scintillometry observations, we argue that a significant source of turbulence aiming at the surface fluxes has origins in the upper level shear-induced thermal turbulence at the top of the ABL.
关键词： stable boundary layer,surface turbulence,optical scintillation,radiative cooling,small scale drainage flows
更新于2025-09-19 17:13:59
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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) - Unravelling Optical and Electrical Degradation of Perovskite Solar Cells and Impact on Perovskite/Silicon Monolithic Tandem Modules
摘要： The simultaneous measurement of heat and light signals from a scintillating crystal was performed at temperatures of tens of milli-kelvin using a scintillating bolometric detector. The crystal was instrumented with a pair of low-temperature detectors, consisting of a metallic magnetic calorimeter for reading the phonon signals and a light detector based on a Ge light absorber, to simultaneously measure the scintillation light and phonon signals. This article presents the principle and performance, such as the event separation capability, of this simultaneous heat/light measurement system.
关键词： low-temperature detector,Calcium molybdate,scintillation crystal,neutrinoless double beta decay,metallic magnetic calorimeters
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Numerical estimation of lattice strain, bending and generation of misfit dislocations in HgCdTe heterostructures grown on GaAs substrate
摘要： This paper is the fifth in a series of articles on the basic physics of light yield nonproportionality in scintillators. Here, we compare and contrast the nonproportionality as registered by gamma rays and high-energy electrons. As has been noted in the past, these two types of data have different curve shapes (for plots of the light yield against electron or gamma energy). Herein, we show how the experimental gamma nonproportionality curve can be calculated from the electron response by accounting for the distribution of high energy electrons created by the gamma photon via the photoelectric interaction. Similarly, we measure and model the gamma-induced resolution as a function of energy and compare this data to predictions from our model. The utility of the model is explored using data acquired with the scintillators (Eu), GYGAG(Ce) and CsI(Na).
关键词： Gamma ray detectors,solid scintillation detectors,luminescence
更新于2025-09-16 10:30:52
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Development of a 3-D scintillator detector for Compton imaging based on laser engraving
摘要： Y2SiO5: Ce (YSO) scintillation with characteristics of high light yield, fast decay time and high Compton scattering fraction shows good application potential for Compton imaging. In this study, we propose a three-dimensional (3-D) scintillator detector, which is segmented by the YSO monolithic rods and pixelated by sub-surface laser engraving (SSLE) in the depth direction. Two arrays of silicon photomultipliers are optically coupled to the YSO array at each end, in which the pixels are designed for a one-to-one match. By identifying the location number of array pixels and measuring depth-of-interaction (DOI) of pixelated scintillator rods, the interaction coordinates of gamma photon can be obtained accurately. After energy consistent calibration, the energy resolutions of the pixels in 3-D detector were evaluated. The imaging test results indicate that the detector has a capability to locate a 0.1 μSv/h Cs-137 gamma-ray source within 90 seconds in 4π field-of-view (FOV). The efficiency of the imaging events is 2.2 %. By using the maximum likelihood expectation maximization (MLEM) algorithm with 10 iterations, the full width at half maximum (FWHM) of the reconstructed hotspot decreases to less than 9.0 °. This configuration mainly simplifies the calculation of interaction coordinates compared to the center of gravity method. Moreover, the higher segment precision for DOI estimation are realized thanks to the SSLE technique. The 3-D scintillator detector achieves 4π Compton imaging with high detection efficiency and high localization accuracy.
关键词： Sub-surface laser engraving,Scintillation detectors,Compton imaging,Image reconstruction
更新于2025-09-12 10:27:22
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Scintillation experiments with non-uniformly and uniformly correlated spatially partially coherent laser beams propagating underwater
摘要： We report on experiments where non-uniformly correlated (NUC), Gaussian Schell (GSM) and Multi-Gaussian Schell (MGSM) model spatially partially coherent laser beams were propagated underwater. Two scenarios were explored: still water and mechanically agitated water. The main objective of our study was the experimental comparison of the scintillation performance among beams with different correlation functions. The results show generally increased absolute values of scintillation index for NUC beams as compared with GSM and MGSM beams. We hypothesized that this effect is related to the method of NUC beams generation. It should be noted, that the presented results document only the given experimental scenarios and show the relative comparison between GSM, MGSM and NUC beams with Gaussian used as a turbulence level benchmark. Further investigation is necessary to broaden the scope of our explorations of the propagation of uniformly correlated spatially partially coherent as well as non-uniformly correlated beam classes.
关键词： multi-Gaussian Schell model beam,Non-uniformly correlated,partial spatial coherence,scintillation,experimental validation,underwater laser propagation
更新于2025-09-12 10:27:22
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Experimental study of the effects of thermally induced optical turbulence on underwater wireless optical communication link parameters
摘要： In this experimental research, the effects of refractive index fluctuations resulting from temperature fluctuations on some of the most important underwater communication link parameters such as the average received power, Signal to Noise Ratio (SNR) and normalized power variance (aperture averaged scintillation) has been experimentally investigated. Moreover, by introducing a new probability density function which is fitted more appropriately to the experimental data obtained from our simulator tank, the Bit Error Rate (BER) behavior of an Underwater Wireless Optical Communication (UWOC) link is also studied. These investigations are essential due to the optical turbulence limiting effects on the performance of UWOC systems. The experimental results indicate that reduction of the aperture averaged scintillation effects by using of optical components in the transmitter and receiver of UWOC links can enhance their performance. In general, increasing the strength of the optical turbulence (by increasing the temperature gradient induced by the rod heater) or the distance of the localized turbulence screen generated by temperature gradient from the transmitter plane, the aperture averaged scintillation decreases and consequently the SNR raises whilst the BER declines. Also, expanding the aperture diameter of the receiver optics reduces the normalized power variance which leads to decrease and increase in the BER and the SNR amounts respectively. The results are presented as experimental simulation graphs.
关键词： Laser beam propagation through turbulence,aperture averaged scintillation,Probability density function,BER,SNR,Underwater optical communication link
更新于2025-09-12 10:27:22
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Scintillation of laser beams carrying orbital angular momentum propagating in a near-maritime environment
摘要： Laser beams carrying orbital angular momentum (OAM) were propagated in a near-maritime environment along an 890 meter link across the Severn River at the United States Naval Academy. The OAM beams were generated using green light ( ?? = 532 nm) and etched spiral phase plates with different topological charges. The light intensity fluctuations of Gaussian and beams carrying OAM with topological charges of 1, 6, and 8 were measured and the scintillation indices of each beam were compared. Additionally, atmospheric turbulence was measured using a co-aligned scintillometer along the 890 meter propagation path. During testing, a wide range of atmospheric conditions occurred and the refractive index structure parameter measurements ranged from 5 × 10?14 down to 5 × 10?15 m ???∕??. Our measurements of transmitted voltage in the radial intensity across the maritime link, and calculated scintillation index, for the Gaussian beam and laser beams carrying OAM indicate a weak reduction in scintillation index for increasing topological charge. To reduce the measurement uncertainty and improve upon statistical significance of our findings, additional testing is needed.
关键词： Orbital angular momentum,OAM,Scintillation,Laser propagation,Near-maritime environment
更新于2025-09-12 10:27:22