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41 results on '"Jun, Qi"'

2. Flat top optical frequency combs based on a single-core quantum cascade laser at the wavelength of ~8.7 μm

Author

Ma Yu, Li Wei-Jiang, Xu Yun-Fei, Liu Jun-Qi, Zhuo Ning, Yang Ke, Zhang Jin-Chuan, Zhai Shen-Qiang, Liu Shu-Man, Wang Li-Jun, and Liu Feng-Qi

Subjects
General Physics and Astronomy
Abstract

We present optical frequency combs with a spectral emission of 48 cm-1 and an output power of 420 mW based on a single-core quantum cascade laser at λ~8.7 μm. A flat top spectrum sustains up to 130 comb modes delivering ~3.2 mW of optical power per mode, making it a valuable tool for dual comb spectroscopy. The homogeneous gain medium, relying on a slightly-diagonal bound-to-continuum structure, promises to provide broad and stable gain for comb operating. Remarkably, the dispersion of this device is measured within 300 fs2/mm to ensure stable comb operation over 90% of the total current range. The comb is observed with a narrow beatnote linewidth around 2 kHz and has weak dependence on the applied current for stable comb operation.

Published
2022

4. Flat Top Optical Frequency Combs Based on a Single-Core Quantum Cascade Laser at Wavelength of ∼ 8.7 μm

Author

Yu Ma, Wei-Jiang Li, Yun-Fei Xu, Jun-Qi Liu, Ning Zhuo, Ke Yang, Jin-Chuan Zhang, Shen-Qiang Zhai, Shu-Man Liu, Li-Jun Wang, and Feng-Qi Liu

Subjects
General Physics and Astronomy
Abstract

We present optical frequency combs with a spectral emission of 48 cm−1 and an output power of 420 mW based on a single-core quantum cascade laser at λ ∼ 8.7 μm. A flat top spectrum sustains up to 130 comb modes delivering ∼ 3.2 mW of optical power per mode, making it a valuable tool for dual comb spectroscopy. The homogeneous gain medium, relying on a slightly diagonal bound-to-continuum structure, promises to provide a broad and stable gain for comb operating. Remarkably, the dispersion of this device is measured within 300 fs2/mm to ensure stable comb operation over 90% of the total current range. The comb is observed with a narrow beatnote linewidth around 2 kHz and has weak dependence on the applied current for stable comb operation.

Published
2023

5. Measurement of Eccentricity of the Centre of Mass from the Geometric Centre of a Sphere

Author

Guo Jun-Qi, GU Bang-Ming, HU Zhong-Kun, and Luo Jun

Subjects
Physics, Balance (metaphysics), Gravitational constant, Classical mechanics, Density distribution, media_common.quotation_subject, Newtonian fluid, General Physics and Astronomy, High Energy Physics::Experiment, Astrophysics::Earth and Planetary Astrophysics, Mechanics, Eccentricity (behavior), media_common
Abstract

The eccentricity of the centre of mass from the geometric centre of a spherical attracting mass in determining the Newtonian gravitational constant G is tested by means of an electronic balance. The experimental result shows that the eccentricity of the sample is about 0.31 μm with uncertainty of 0.05 μm. Two density distribution models are discussed to estimate the uncertainty to G by the eccentricities of the attracting masses.

Published
2004

10. From the Anti-Yang Model to the Anti-Snyder Model and Anti-De Sitter Special Relativity

Author

Xin-An Ren and Wei-Jun Qi

Subjects
Physics, De Sitter space, Duality (projective geometry), Minkowski space, General Physics and Astronomy, Anti-de Sitter space, Space (mathematics), Special relativity (alternative formulations), de Sitter invariant special relativity, Projective geometry, Mathematical physics
Abstract

Based on Yang's quantized space-time model, a complete Yang model from (5+1)-dimensional space with Minkowski signature is discussed using the projective geometry method and Dirac procedure. We introduce an anti-Yang model and an anti-Snyder model to discuss the duality relations between the anti-Snyder model and anti-de Sitter special relativity.

Published
2013

11. Room-Temperature Ferromagnetism in Fe/Sn-Codoped In2O3Powders and Thin Films

Author

Min-Gang Zhang, Shi-Bo Xi, Jun-Qi Zhou, Xiu-Fang Qin, Rong-Rong Ma, Xiao-Chen Fan, Feng-Xian Jiang, and Xiaohong Xu

Subjects
Materials science, Absorption spectroscopy, Condensed matter physics, Analytical chemistry, General Physics and Astronomy, Pulsed laser deposition, Condensed Matter::Materials Science, Magnetization, Ferromagnetism, Vacuum annealing, Impurity, Condensed Matter::Superconductivity, Condensed Matter::Strongly Correlated Electrons, Thin film, Magnetic impurity
Abstract

Fe/Sn-codoped In2O3 powders and films are prepared by a vacuum annealing process and a pulsed laser deposition technique, respectively. The structural and magnetic properties of the samples are investigated. The obvious room-temperature ferromagnetism is observed in both (In0.92Fe0.05Sn0.03)(2)O-3 powders and films, but their magnetic behaviors are very different. The ferromagnetism of the vacuum-annealed powders is partially due to precipitated Fe3O4 impurity. By contrast, the ferromagnetism of the films is intrinsic and does not originate from any magnetic impurity, as confirmed by the extensive x-ray absorption spectroscopy and magnetization studies.

Published
2013

19. The Plateau of Moment of Inertia and the Energy Gap in 161–168 Yb

Author

Yan-Jun Qi, Li-Xun Huang, Shu-Xin Liu, and Tao Li

Subjects
Physics, Proton, Condensed matter physics, Band gap, Hadron, Fermi level, General Physics and Astronomy, Fermi surface, Moment of inertia, Plateau (mathematics), symbols.namesake, symbols, Atomic physics, Nucleon
Abstract

The influence of the gap at Z = 70 on the alignment in 161–168Yb is studied using the particle number conserving method. If there is a gap at the Fermi surface, the occupation probability of the [523]7/2 proton orbital does not change as much as when there is no gap. The formation of the plateau of moment of inertia is sensitive to the relative position of the orbital π[404]7/2, π[411]1/2 and π[523]7/2. A third backbending caused by π[541]1/2 is predicted.

Published
2011

22. Magneto-optical Kerr Effect in Co/Alq 3 Granular Films

Author

Sheng Peng, Yin Jian-Fang, Wang Song-You, Ni Gang, Yuan Ming-Yun, WU Jun-Qi, and Jin Qing-Yuan

Subjects
Physics, Kerr effect, Magneto-optic Kerr effect, Spectrometer, Condensed matter physics, Ellipsometry, Analytical chemistry, General Physics and Astronomy, Photon energy, Rotation, Microstructure, Spectral line
Abstract

A series of Co/Alq3 granular film samples are prepared using co-evaporating technique. The microstructures and magnetic properties are investigated. The Kerr spectra and optical constants of Cox (Alq3)1–x (0.19 ≤ x ≤ 1) granular films are measured using a magneto-optical Kerr spectrometer and a spectroscopic ellipsometer in the 1.5–4.5 eV photon energy range. The Kerr rotation reaches the maximum value of 0.5° in the x = 0.65 sample. The relationship between enhanced Kerr rotation and optical constants is discussed, and the concentration dependence of MOKE spectra is also investigated.

Published
2009

25. Multi-Electron Processes in 4.15–11.08 keV/ u 13 C 6+ on Argon Collisions

Author

Fang-Fang, Ruan, primary, Xiao-Hong, Cai, additional, De-Yang, Yu, additional, Rong-Chun, Lu, additional, Cao-Jie, Shao, additional, Ming-Sheng, Li, additional, Hong-Qiang, Zhang, additional, Ying, Cui, additional, Jian-Xiong, Shao, additional, Bao-Wei, Ding, additional, Ying-Li, Xue, additional, De-Jun, Qi, additional, Zhi-Hu, Yang, additional, and Xi-Meng, Chen, additional

Published
2007
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35. Room-Temperature Ferromagnetism in Fe/Sn-Codoped In2O3 Powders and Thin Films.

Author

JIANG Feng-Xian, XI Shi-Bo, MA Rong-Rong, QIN Xiu-Fang, FAN Xiao-Chen, ZHANG Min-Gang, ZHOU Jun-Qi, and XU Xiao-Hong

Subjects
FERROMAGNETISM, TEMPERATURE effect, IRON, TIN, DOPED semiconductors, INDIUM oxide, POWDER metallurgy, THIN films, ANNEALING of metals, PULSED laser deposition
Abstract

Fe/Sn-codoped In2O3 powders and films are prepared by a vacuum annealing process and a pulsed laser de-position technique, respectively. The structural and magnetic properties of the samples are investigated. The obvious room-temperature ferromagnetism is observed in both (In0.92Fe0.05Sn0.03)2O3 powders and films, but their magnetic behaviors are very different. The ferromagnetism of the vacuum-annealed powders is partially due to precipitated Fe3O4 impurity. By contrast, the ferromagnetism of the ñlms is intrinsic and does not originate from any magnetic impurity, as confirmed by the extensive x-ray absorption spectroscopy and magnetization studies. [ABSTRACT FROM AUTHOR]

Published
2013
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36. High Power Surface Metal Grating Distributed Feedback Quantum Cascade Lasers Emitting at &lgr; ∼ 8.3 &mgr;m.

Author

Dan-Yang Yao, Feng-Qi Liu, ZHANG Jin-Chuan, Li-Jun Wang, Jun-Qi Liu, and Zhan-Guo Wang

Subjects
QUANTUM cascade lasers, DIFFRACTION gratings, METAL coating, REFLECTANCE, TEMPERATURE effect, LASER beams
Abstract

We present a surface metal grating distributed feedback quantum cascade laser emitting at &lgr;∼8.3&mgr;m and operating above 400K in pulsed mode. A very high peak power of 463mW at 290K and still more than 18mW at 400K is achieved for a high-reflectivity-coated 13-&mgr;m-wide and 2.5-mm-long laser. Single-mode emission with a high side mode suppression ratio and wide temperature tuning range is observed. Such a high-power single-mode laser with a simple device process is important for practical applications. [ABSTRACT FROM AUTHOR]

Published
2012
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37. High-Power High-Temperature Continuous-Wave Operation of Quantum Cascade Laser at &lgr;∼4.6 &mgr;m without Lateral Regrowth.

Author

Liang Ping, Liu Feng-Qi, Zhang Jin-Chuan, Wang Li-Jun, Liu Jun-Qi, and Wang Zhan-Guo

Subjects
HIGH temperatures, CONTINUOUS wave lasers, QUANTUM cascade lasers, MOLECULAR beam epitaxy, SURFACE coatings, GEOMETRY
Abstract

High-power quantum cascade lasers (&lgr; = 4.6 &mgr;m) working in continuous wave (cw) up to 90°C are presented. The material was grown by solid-source molecular beam epitaxy and processed into narrow conventional ridge geometry without lateral regrowth. High cw output power of 850mW at 10°C and more than 200mW at 90°C were obtained with threshold current densities of 1.34 and 2.47 kA/cm2, respectively, for a high-reflectivity-coated 12-&mgr;m-wide and 3-mm-long laser. [ABSTRACT FROM AUTHOR]

Published
2012
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40. Confined and Interface Phonons in Chirped GaAs-AlGaAs Superlattices.

Author

Yong-Zheng Hu, Feng-Qi Liu, Li-Jun Wang, Jun-Qi Liu, and Zhan-Guo Wang

Subjects
PHONON spectra, PERFORMANCE of quantum cascade lasers, SEMICONDUCTOR lasers, SPECTRUM analysis, SUPERLATTICES, SEMICONDUCTORS, OPTICAL properties measurement
Abstract

The confined longitudinal optical, transverse optical and interface phonon modes in chirped GaAs-AlGaAs superlattices grown on the (001)-oriented GaAs substrate are studied by the micro-Raman spectroscopy. The phonon modes are probed at the (001) and (11̄0) faces. The temperature dependence of the longitudinal optical, transverse optical and interface phonon modes are achieved. The temperature dependence of the longitudinal optical phonon frequencies demonstrates that a tensile strain exists in the GaAs layers of the chirped superlattices, which is significant for analyzing the device failure of a terahertz quantum cascade laser. [ABSTRACT FROM AUTHOR]

Published
2014
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