Recently a new Thomson scattering diagnostic system was upgraded in EAST tokamak experiment using a multipulse Nd:YAG (neodymium-yttrium aluminium garnet) laser and a multipoint observation volumes. This diagnostic uses a new optical laser alignment technique that was made to determine accurately the laser position, and a new lens collection system that enables the measurement of wider plasma's object. A composite control system made we can get the results in several seconds. Furthermore, a new data processing method was adopted for much exact results.
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http://dx.doi.org/10.1063/1.3599039 | DOI Listing |
We present a spectroscopic method that employs a single linearly chirped laser pulse (LCLP) generated by external modulation to realize long-distance multi-point gas sensing. Even without frequency-chirping calibration, accurate single-shot spectral measurement is rendered possible by the high linearity of intrapulse chirping (linearity error of ∼10). Utilizing the LCLP's built-in capacity of time-division-multiplexing, high measurement sensitivity is guaranteed by introducing a multichannel intensity noise compensation mechanism.
View Article and Find Full Text PDFCoherent reception, along with time- and wavelength-division multiplexing (TWDM), is a promising concept to simultaneously support multiple services in future high-speed point-to-multipoint passive optical networks (PONs). The next-generation PON 2 (NG-PON2) standard describes a TWDM-PON based on IM/DD intensity modulation and direct detection (IM/DD) which employs tunable-lasers and optical filters such as tunable optical filters or cyclic arrayed-waveguide gratings. Here, we investigate what we believe to be a novel coherent TWDM-PON architecture based on a frequency comb source in the optical line terminal (OLT), and thermally-tuned distributed-feedback (DFB) lasers in the optical network units (ONUs).
View Article and Find Full Text PDFUltrasonics
October 2023
School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen, China; Guangdong Provincial Key Laboratory of Intelligent and Resilient Structures for Civil Engineering, Harbin Institute of Technology, Shenzhen, China.
For ultrasonic non-destructive testing, the development of miniaturized, embeddable, and distributed ultrasonic transducers has always been a hot research topic. In light of this, a novel fiber optic laser-ultrasonic transducer, employing the long-period fiber grating (LPFG), was introduced in this study to facilitate the implementation of embedded and distributed applications. LPFG couples the light transmitted in the optical fiber into the photoacoustic conversion material.
View Article and Find Full Text PDFRev Sci Instrum
October 2024
MOE Key Laboratory of Fundamental Physical Quantities Measurement and Hubei Key Laboratory of Gravitation and Quantum Physics, PGMF, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
High-precision phasemeters are a key technology in intersatellite laser interferometers used for detecting gravitational waves (GWs) in space. As the core of the readout system, the phasemeter must operate in the bandwidth of 5-25 MHz, and its resolution needs to reach the order of μrad/Hz at mHz. It presents significant challenges to electronic signal processing technology.
View Article and Find Full Text PDFClin Otolaryngol
January 2025
Charing Cross Hospital, Imperial College Healthcare NHS Trust, London, UK.
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