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1.
热声现象的一种非线性模型的研究   总被引:1,自引:0,他引:1  
本文对一种准一维非线性热声模型进行研究,利用该模型初步预测了一种热声驱动器的工作特性,并采用一种更简便的差分格式对系统中发生的非线性现象进行了数值模拟。结果表明,在频域内和线性条件下,该模型简化为经典的线性热声模型,可以预测热声驱动器的起振温度梯度;在时域内和非线性条件下,该模型可以模拟热声系统内的瞬态压力波由初始增长,经过非线性演化,最终达到饱和的全过程;最后,还讨论了板叠上的温度差对饱和压力波的影响。  相似文献
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An erbium-doped phosphate glass fibre has been drawn by the rod-in-tube technique in our laboratory. The gain for the Er^3+-doped phosphate glass fibre with different pump powers and with different input signal wavelengths is investigated. The 2.2-cm-long fibre, pumped by a single-mode 980-nm fibre-pigtailed laser diode, can provide a net gain per unit length greater than 1.SdB/cm. The pump threshold is about 50mW at the wavelength of 1534nm, and below 70roW at 1550nm. The gain linewidth of the Er^3+-doped phosphate glass fibre is greater than 34 nm and can cover the C band in optical communication networks.  相似文献
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This paper reports on the fabrication and characterization of a newly erbium-doped single-mode tellurite glass-fibre applicable for 1.5-μum optical amplifiers. A very broad erbium amplified spontaneous emission in the range 1450--1650nm from erbium-doped single-mode tellurite glass-fibre is obtained upon excitation of a 980-nm laser diode. The effects of the length of glass-fibre and the pumping power of laser diode on the amplified spontaneous emission are discussed. The result indicates that the tellurite glass-fibre is a promising candidate for designing fibre-optic amplifiers and lasers.  相似文献
5.
徐善羡  荆继良 《中国物理》2005,14(12):2415-2420
The energy of the stationary axisymmetric Einstein-Maxwell dilation-axion (EMDA) black hole is studied in the context of the Hamiltonian formulation of the teleparallel equivalence of general relativity (TEGR). The energy expression for the finite and arbitrary space-like two spheres is exactly computed by means of the integral form of the constraint equations of the formalism naturally without any restriction on the metric parameters. We also show that our results give the same values obtained by other methods for some special cases.  相似文献
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以原子物理学理论为基础,详细地给出了在红外光谱之外原子材料紫外光谱的产生方法,列出了计算数据,给出了实验的结果。  相似文献
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We experimentally study a novel fibre with high gain per unit length based on the homemade erbium--ytterbium codoped phosphate glass. The gain and noise characterizations with different pump powers at different wavelengths are investigated. The 1.8-cm-long fibre, dual-pumped by two single mode 980-nm fibre-pigtailed laser diodes, provides a gain per unit length greater than 3.0dB/cm and a noise figure less than 6.5dB. The gain saturation behaviour at 1535nm is obtained and the saturation output power (3dB compression) is greater than 5dBm.  相似文献
8.
We experimentally study a novel fibre with high gain per unit length based on the homemade erbium-ytterbium codoped phosphate glass. The gain and noise characterizations with different pump powers at different wavelengths are investigated. The 1.8-cm-long fibre, dual-pumped by two single mode 980-nm fibre-pigtailed laser diodes, provides a gain per unit length greater than 3.0dB/cm and a noise figure less than 6.SdB. The gain saturation behaviour at 1535nm is obtained and the saturation output power (3 dB compression) is greater than 5 dBm.  相似文献
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In this paper, we introduce the generalized photon-modulated squeezed thermal states (GPMSTS) obtained by repeatedly acting the combination of Bosonic creation and annihilation operation on the squeezed thermal state. We investigate the nonclassical properties of GPMSTS and its decoherence in a thermal environment according to the negative region of Wigner function. It is found that the normalization factor of GPMSTS is a Legendre polynomial. Especially, the decoherence effect is discussed by deriving the time evolution of the Wigner function.  相似文献
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