- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2019
- 2017
- Phased-array
- Ultrasound-guided high-intensity focused ultrasound (USgHIFU)
- Targeting accuracy
- Calibration
- cryostat
- low intensity low temperature
- space solar cells
- LILT
- solar cell characterization
- FSO Communication System
- Optoelectronic Information Science and Engineering
- Electrical Engineering and Automation
- Galgotias College of Engineering and Technology
- Shanghai Jiao Tong University
- Fraunhofer Institute for Solar Energy Systems ISE
-
Influence of Laser Intensity Fluctuation on Single-Cesium Atom Trapping Lifetime in a 1064-nm Microscopic Optical Tweezer
摘要： An optical tweezer composed of a strongly focused single-spatial-mode Gaussian beam of a red-detuned 1064-nm laser can con?ne a single-cesium (Cs) atom at the strongest point of the light intensity. We can use this for coherent manipulation of single-quantum bits and single-photon sources. The trapping lifetime of the atoms in the optical tweezers is very short due to the impact of the background atoms, the parametric heating of the optical tweezer and the residual thermal motion of the atoms. In this paper, we analyzed the in?uence of the background pressure, the trap frequency of optical tweezers and the laser intensity ?uctuation of optical tweezers on the atomic trapping lifetime. Combined with the external feedback loop based on an acousto-optical modulator (AOM), the intensity ?uctuation of the 1064-nm laser in the time domain was suppressed from ±3.360% to ±0.064%, and the suppression bandwidth in the frequency domain reached approximately 33 kHz. The trapping lifetime of a single-Cs atom in the microscopic optical tweezers was extended from 4.04 s to 6.34 s.
关键词： optical tweezer,suppression of laser intensity ?uctuation,parametric heating,atomic trapping lifetime
更新于2025-09-19 17:13:59
-
Investigation of 3 dB Optical Intensity Spot Radius of Laser Beam under Scattering Underwater Channel
摘要： An important step in the design of receiver aperture and optimal spacing of the diversity scheme for an underwater laser communication system is to accurately characterize the two-dimensional (2D) spatial distribution of laser beam intensity. In this paper, the 2D optical intensity distribution and 3 dB optical intensity spot radius (OISR) are investigated due to the dominating optical intensity of laser beam being within the 3 dB OISR. By utilizing the Henyey–Greenstein function to compute the scattering angles of photons, the effects of the scattering underwater optical channel and optical system parameters on 3 dB OISR are examined based on the Monte Carlo simulation method. We have shown for the ?rst time that in the channel with a high density of scattering particles, the divergence angle of the laser source plays a negligible role in 3 dB OISR. This is an interesting phenomenon and important for optical communication as this clearly shows that the geometric loss is no longer important for the design of receiver aperture and optimal spacing of the diversity scheme for the underwater laser communication system in the highly scattering channel.
关键词： 3 dB optical intensity spot radius,scattering underwater channel,Monte Carlo simulation method
更新于2025-09-19 17:13:59
-
Research on Power Equalization of Three-phase Cascaded H-Bridge Photovoltaic Inverter Based on the Combination of Hybrid Modulation Strategy and Zero-Sequence Injection Methods
摘要： We demonstrate for the ?rst time an intensity-modulated direct-detection link using four states of polarization. The four data-independent tributaries are each assigned distinct states of polarization to enable the receiver to separate the signals. Polarization rotation due to propagation over optical ?ber is tracked and compensated with simple digital signal processing in Stokes space. Transmission below the forward error correction limit is shown for maximum net bitrates of 100 Gb/s (4 × 27 GBd) and 120 Gb/s (4 × 32 GBd) over 2-km standard single-mode ?ber at a center wavelength of 1550 nm.
关键词： direct detection (DD),intensity modulation (IM),digital signal processing,Stokes space,100G,polarization
更新于2025-09-19 17:13:59
-
Terahertz radiation enhanced by target ablation during the interaction of high intensity laser pulse and micron-thickness metal foil
摘要： When an ultra-intense relativistic laser is irradiated on a solid target, terahertz (THz) pulses can be generated by coherent transition radiation when the laser-driven electron beams cross the rear surface of the target. The radiation energy depends on the number and energy of the electrons. By introducing a milli-joule picosecond ablation laser pulse, an underdense preplasma with a scale length of micrometers is generated at the front surface of the target. Electron beams with more charge and higher energy can be produced during the interaction between the following main laser pulse and the preplasma, which enhance the THz radiation and affect the radiation angle. Two dimensional particle-in-cell simulations demonstrate the improvement of electron beams and a nearly tenfold enhancement of THz radiation energy is observed.
关键词： high intensity laser pulse,particle-in-cell simulations,coherent transition radiation,terahertz radiation,target ablation,micron-thickness metal foil
更新于2025-09-19 17:13:59
-
Pulsed Nd:YAG laser: effects on pain, postural stability, and weight-bearing pattern in children with hemophilic ankle arthropathy
摘要： Hemophilic ankle arthropathy features joint pain, impaired postural control, and abnormal weight-bearing pattern. This study was designed to investigate the effects of pulsed Nd:YAG laser on pain, postural stability, and weight-bearing pattern in children with hemophilic ankle arthropathy. Forty children diagnosed with hemophilia type A (age, 8–16 years) were randomly allocated to either the treatment group (n = 20) who received a three-phase active therapy with pulsed Nd:YAG laser thrice/week (total energy was 1500 J) plus a physical exercise program for four consecutive weeks, or the placebo group (n = 20) who received placebo laser plus the physical exercise program. Pain, postural control (i.e., directional control [DC], endpoint excursion [EE], center-of-gravity movement velocity [CoG-MV], and maximum excursion [MXE]), and weight-bearing pattern (i.e., pressure peaks of the hindfoot [PP-HF] and forefoot [PP-FF], and the foot contact area [FCA]) were assessed pre- and post-treatment. The treatment group showed greater improvement in pain (P = .004), DC (P = .02), EE (P = .003), and CoG-MV (P = .003) compared to the placebo group. However, there was no statistically significant difference between both groups regarding the MXE (P = .15). In addition, the treatment group achieved favorable improvements in PP-HF (P = .003), PP-FF (P = .027), and FCA (P = .002) relative to the placebo group. Pulsed Nd:YAG laser is a potentially effective therapy for pain relief, postural control enhancement, and weight-bearing pattern adjustment in children with hemophilic ankle arthropathy.
关键词： Dynamic stability limits,Hemophilia,Plantar pressure,High-intensity laser therapy,Joint inflammation
更新于2025-09-19 17:13:59
-
A Greenhouse Test to Explore and Evaluate Light-Emitting Diode (LED) Insect Traps in the Monitoring and Control of Trialeurodes vaporariorum
摘要： Population control of small sucking insects has been challenging, and alternative control methods are constantly being sought. Visual traps have long been used to monitor and control pests. Colored sticky cards are widely used for diurnal pests, but their effects are influenced by environmental light conditions. Artificial light traps are mostly used for nocturnal pests. Here, we explored and evaluated light-emitting diode (LED) traps for the monitoring and control of small diurnal sucking insects using greenhouse tests targeting the greenhouse whitefly Trialeurodes vaporariorum. We tested the trapping efficacy of the LED water pan trap, assessed the most attractive LED light and analyzed its efficacy under different weather conditions. The results showed that the LED water pan trap was too inefficient to be useful. Green LEDs were more attractive than yellow LEDs, UV LEDs and green-UV combinations. Regardless of sunny or cloudy conditions, the green LED trap caught more than twice the number of whiteflies than the yellow sticky card alone under summer shading conditions. Our study suggests that LED traps have a significant field application value in whitefly mass trapping and may also be efficient for other diurnal insects. The design of LED traps specific for diurnal insects is discussed.
关键词： phototaxis,attractive light,field evaluation,light trap,environment light intensity
更新于2025-09-19 17:13:59
-
Physics of Electrostatic Projection Revealed by High-Speed Video Imaging
摘要： Processes based on electrostatic projection are used extensively in industry, e.g., for mineral separations, electrophotography, or manufacturing of coated abrasives, such as sandpaper. Despite decades of engineering practice, there are still unanswered questions. In this paper, we present a comprehensive experimental study of the projection process of more than 1500 individual spherical alumina particles with a nominal size of 500 μm, captured by high-speed video imaging and digital image analysis. Based on flight trajectories of approximately 1100 projected particles, we determine the acquired charge and dynamics as a function of the relative humidity (RH) and the electric field intensity and compare the results with classical theories. For RH levels of 50% and above, more than 85% of distributed particles are projected, even when the electric field intensity is at its minimum level. This suggests that, beyond a critical value of the electric field intensity, the RH plays a more critical role in the projection process. We also observe that the charging time is reduced dramatically for RH levels of 50% and above, possibly due to the buildup of thin water films around the distributed particles, which can facilitate charge transfer. In contrast, projected particles at the 30% RH level exhibit excessive amounts of electric charge, between 2 and 4 times than that of the saturation value, which might be attributed to triboelectric charging effects. Finally, the physics of electrostatic projection is compared and contrasted with those of induced-charge electrokinetic phenomena, which share similar field-square scaling, as the applied electric field acts on its own induced charge to cause particle motion.
关键词： electric field intensity,high-speed video imaging,alumina particles,charge transfer,electrostatic projection,triboelectric charging,relative humidity
更新于2025-09-19 17:13:59
-
[IEEE 2019 IEEE Eurasia Conference on IOT, Communication and Engineering (ECICE) - Yunlin, Taiwan (2019.10.3-2019.10.6)] 2019 IEEE Eurasia Conference on IOT, Communication and Engineering (ECICE) - Negative photoresist micro-lens for enhancing fiber-coupled InGaAs/AlGaAs MQW LED performance
摘要： The feasibility of using DNR-L300 negative photoresist to fabricate the micro-lens on InGaAs/AlGaAs MQW LED for enhancing the fiber-coupled LED performance was studied in this report. The measurement results indicate that the transmittance of DNR-L300 photoresist can reach nearly 90 percent and remains unchanged as long as the wavelength is longer than 800 nm. Thus, the infrared light-emitting diode with an emission wavelength peak at 917 nm is adopted for this study. By controlling developing time and melting process, the lens diameter and height were characterized via Dektak profilometer and optical microscope so as to obtain the optimum condition for forming micro lenses. The experiment results show that the micro-lens thickness as high (cid:2)(cid:3) (cid:4) (cid:5) (cid:6)(cid:7) (cid:8) (cid:9) (cid:4) (cid:10)(cid:11)uld be achieved by performing the melting temperature at 200 °C for 10 minutes after the photolithographic process. In addition, by using such a thick micro-lens fabricated from negative photoresist, more than 30% increase of fiber-coupled LED output intensity could be obtained as compared with those without having micro-lens. More details of the experimental results will be revealed and discussed in this report.
关键词： Micro-lens LED,Negative photoresist,Fiber-coupled intensity
更新于2025-09-19 17:13:59
-
[IEEE 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Shenzhen, China (2019.11.25-2019.11.27)] 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Effects of LED Light Color and Intensity on Feather Pecking and Fear Responses of Layer Breeders in Natural Mating Colony Cages
摘要： Natural mating colony cages for layer breeders have become commonplace for layer breeders in China. However, feather pecking (FP) and cannibalism are prominent in this system. The objective of this study was to investigate the effects of 4 LED light colors (white: WL, red: RL, yellow-orange: YO, blue-green: BG) with 2 light intensities for each color on FP, plumage condition, cannibalism, fear, and stress. A total of 32 identical cages were used for the 8 treatments (4 replicates for each treatment). For both light intensities, hens in RL had a lowest frequency of severe FP, whereas hens in WL had a highest frequency of severe FP. Hens in RL and BG had a better plumage condition than in WL and YO. Compared with RL and BG, hens in WL and YO had a significant longer TI duration. Hens in RL had a higher concentration of 5-HT, a lower concentration of CORT, and a lower heterophil to lymphocyte ratio than WL and YO. Furthermore, RL could significantly reduce mortality from cannibalism. Overall, hens treated with RL and low light intensity showed a lower frequency of severe FP, less damaged plumage, were less fearful, and lower physiological indicators of stress, and had reduced mortality from cannibalism. Transforming the light color to red or dimming the light could be regarded as an effectively method to reduce the risk of FP and alleviate the fear responses of layer breeder.
关键词： LED light color,natural mating colony cages,layer breeders,light intensity,fear responses,feather pecking
更新于2025-09-19 17:13:59
-
Modeling of the 3D spatio-temporal thermal profile of joule-class -based laser amplifiers
摘要： Thermal pro?le modi?cation of an active material in a laser ampli?er via optical pumping results in a change in the material’s refractive index, and causes thermal expansion and stress, eventually leading to spatial phase aberrations, or even permanent material damage. For this purpose, knowledge of the 3D spatio-temporal thermal pro?le, which can currently only be retrieved via numerical simulations, is critical for joule-class laser ampli?ers to reveal potentially dangerous thermal features within the pumped active materials. In this investigation, a detailed, spatio-temporal numerical simulation was constructed and tested for accuracy against surface thermal measurements of various end-pumped Yb3+-doped laser-active materials. The measurements and simulations show an excellent agreement and the model was successfully applied to a joule-class Yb3+-based ampli?er currently operating in the POLARIS laser system at the Friedrich-Schiller-University and Helmholtz-Institute Jena in Germany.
关键词： diode-pumped solid-state lasers,ytterbium,laser ampli?ers,spatio-temporal thermal pro?le modeling,high intensity lasers
更新于2025-09-19 17:13:59