共查询到20条相似文献,搜索用时 58 毫秒
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提出一种新型的基于半导体光纤环形腔激光器(semiconductor fiber ring laser, SFRL)全光超宽带(ultra-wideband, UWB)信号源的方案,该方案可以同时产生3路高斯脉冲一阶导数脉冲(monocycle) UWB信号.建立了这种全光UWB信号源的宽带理论模型,通过数值模拟的方法研究SFRL中的半导体光放大器(semiconductor optical amplifier, SOA)的注入电流、激射光波长、输入信号光功率和波长对monocycle信号性能的影响.结果表明:SOA的注入电流在200—220 mA时可以获得对称性较好的monocycle脉冲;输出monocycle脉冲平均功率和正、负脉冲振幅随激射光波长增加而增加;较低的输入信号光功率可以获得性能较好的monocycle信号;输入信号光波长对输出monocycle信号有一定的影响,但影响很小. 相似文献
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量子点半导体光放大器(QD-SOA)具有皮秒级的增益恢复时间和超快的载流子浓度恢复等特点,光子晶体(PC)与QD-SOA结合后具有强非线性效应、低吸收损耗、高功率传输和低功耗等优点。研究了光子晶体-量子点半导体光放大器(PC-QDSOA)的波长转换特性,详细分析了最大模式增益、泵浦光功率、探测光功率、有源区长度对PC-QDSOA波长转换Q因子的影响及注入电流、泵浦光功率、探测光功率、有源区长度与PC-QDSOA波长转换消光比的关系,并将PC-QDSOA仿真结果与QD-SOA的仿真结果进行比较。结果显示PC-QDSOA的Q因子和消光比的数值总是大于QD-SOA,说明PC-QDSOA比QD-SOA的输出信号质量更好,信号传输效率更高,转换性能更优越。研究结果对PC-QDSOA的应用具有一定的指导意义。 相似文献
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基于光纤中受激喇曼散射效应,运用级联同种光纤设计出全光多波长转换耦合器,使转换输出的各路信号光功率相等.建立了全光多波长转换设计方案的理论模型,给出了设计原理框图以及实现方法,并以1路泵浦信号光、4路连续探测光为例,通过OptiSystem软件进行了仿真,仿真结果表明:所设计的全光多波长转换耦合器能同时对4路探测光实现波长转换,转换输出的信号光码型和输入泵浦信号光码型基本一致;转换效率和消光比随着探测光波长的增大而增大,最大值分别为-34dB和36.68dB;Q因子随着探测光波长的增大而减少,最大值为128.29;在级联光纤之后,4路输出信号光峰值功率和消光比基本相等,Q因子整体数值相对于全光多波长转换后有所下降,最大值为89.5455,验证了该方案的可行性. 相似文献
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在傍轴近似条件下建立了OPO的数学模型,通过引入三波混频中时间与空间关系,采用分步傅里叶算法模拟了纳秒级脉冲和连续光波在谐振腔内的三波混频过程。理论模型中考虑了不同频率光波之间的色散关系,可以在高转换效率情况下分析不同泵浦脉冲功率、脉冲时长、腔镜透反射比以及不同种子光输入等情况下的输出波形、功率以及OPO阈值等特性。实验中采用掺杂MgO的周期性极化铌酸锂晶体(MgO∶PPLN)为非线性介质,在输入1.06 m泵浦激光脉冲能量为0.4 mJ时,产生3.8 m闲频光超过0.07 mJ输出,与数值模拟结果0.08 mJ较为符合。 相似文献
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多电极半导体光放大器对增益特性的改善 总被引:4,自引:4,他引:0
提出了采用多电极实现电流非均匀注入来改变半导体光放大器(SOA)内部的载流子分布,从而改变其增益饱和特性的一种新的方案.用SOA分段模型的计算结果表明,与单电极均匀注入电流的SOA 相比,在同样的总注入电流下,对一个两电极SOA采用前面小后面大的非均匀电流注入,可以提高饱和输出功率和饱和输入功率.而采用前面大后面小的电流注入方式,则将使SOA更容易发生饱和,不仅饱和输出功率与饱和输入功率减小,而且增益谱在饱和后的压缩程度加大,增益谱压缩的对称性提高.对多电极SOA,可以方便灵活地调节各节之间的长度比和注入电流比来满足不同的应用要求. 相似文献
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Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide 总被引:1,自引:0,他引:1
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs. 相似文献
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A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users. 相似文献
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S. G. Nedel’ko M. A. Krysyuk A. L. Apanasenko L. N. Lymarenko Z. T. Moroz 《Journal of Applied Spectroscopy》1997,64(1):55-61
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped
with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly
described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation
(5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum
cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics
of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure
crystals is analyzed (preliminarily).
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997. 相似文献
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A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output. 相似文献
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The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper. 相似文献
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We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed. 相似文献
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Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell. 相似文献
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A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques. 相似文献
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Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing. 相似文献