共查询到20条相似文献,搜索用时 15 毫秒
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Anne-Laure Billabert Quentin Levesque Mourad Chtioui Catherine Algani Christian Rumelhard Alexandre Marceaux Thomas Merlet 《电信纪事》2013,68(1-2):73-79
This paper studies a microwave photonic link built as an IM/DD or intensity modulation–direct detection semiconductor laser system. The radiofrequency gain and 1 dB compression point of the link are both simulated with a modelling approach and compared to measurements. The electrical model of the electro-optic transducer, a distributed feedback laser, is first presented. Taking into account the nonlinearities and noise sources, it is developed on the commercial electrical software Advanced Design System. Owing to this accurate model, the impact of the relaxation oscillation frequency is presented on the system nonlinearity characteristic as for example the input 1 dB compression point. The comparison of simulated results to measured ones confirms the accuracy of this model. 相似文献
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激光冲击处理1Cr11Ni2W2MoV不锈钢 总被引:16,自引:6,他引:10
对1Cr11Ni2W2MoV马氏体不锈钢进行了激光冲击处理(LSP)的基础性研究。激光器最大输出能量为50J,激光功率密度3.7~7.5GW/cm2。吸收层和约束层分别选取Al箔和均匀流水层,激光束采用倾斜入射方式,实验对单光斑试样、搭接光斑试样、疲劳试样分别进行冲击。通过表面形貌、显微硬度和残余应力等检测,验证了激光功率密度对冲击区性能的影响。三组疲劳试件进行对比表明,先冲击后打孔试件的疲劳性能最好,其表面高幅值的残余压应力层能很好地抑制疲劳裂纹的萌生和延长裂纹扩展的速率。实验证明激光冲击处理可以有效提高马氏体不锈钢的疲劳性能。 相似文献
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A report is presented on the first Q -switched laser operation of a room temperature CW diode-pumped Nd:YAB laser. The intense peak fundamental power obtained by Q -switching significantly enhances the green light output from the Nd:YAB laser through the second harmonic conversion process. A peak green power exceeding 3 W was obtained with a CW diode laser input power of 180 mW, as compared to a green output power of only about 1 mW under pure CW operation. Nd:YAB shows considerable promise as a room temperature self-doubling material. Diode-laser-pumped Nd:YAB lasers show promise as compact, and reliable green sources for practical applications 相似文献
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激光焦点位置的检测与控制是激光切割系统中的关键技术之一.在介绍了国内外现有检测方法的基础上,提出一种基于CCD的激光切割焦点位置控制系统.该系统采用激光三角测量法原理,并以CCD成像系统配合数字图像处理技术.实现对激光切割焦点位置的精确测量和控制。 相似文献
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Fan Tso Yee 《Quantum Electronics, IEEE Journal of》1988,24(12):2345-2349
Modeling of Q -switched laser operation for four-level lasers with finite lower-laser-level lifetime is presented. Extraction efficiency is reduced and pulse shape altered in comparison to the case of infinitely fast lower-level relaxation. This reduction in efficiency is dependent on the ratio of the lower state lifetime to the cavity lifetime, the number of times above threshold, and occupancy factors of the upper and lower laser manifolds. The model is applied to the case of a Nd:YAG laser operating at 1.064 μm. At worst, the extraction efficiency is 68% of that expected for infinitely fast relaxation 相似文献
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文献[1~2]报导了等效光束质量因子M~2_e<1的激光束,并称之为"超衍射极限"的光束.本文模拟计算出一种M~2_e<1而M~2>1的激光束,从而说明M~2_e<1与M~2<1并不"等效".M~2_e<1的激光束其M~2是否也<1是一个尚待澄清的问题。 相似文献
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Design and analysis of spectral beam combining system for fiber lasers based on a concave grating 下载免费PDF全文
A novel fiber laser spectral beam combining scheme based on a concave grating is presented.The principle of the presented system is analyzed,and a concave grating with blazed structure for spectral beam combining is designed.The combining potential of the system is analyzed,and the results show that 39 Yb-doped fiber laser can be spectrally beam combined via the designed system.By using scalar diffraction theory,the combining effect of the system is analyzed.The results show that the diffraction efficiency of the designed concave grating is higher than 72% over the whole gain bandwidth,and the combining efficiency is 73.4%.With output power of 1 kW for individual fiber laser,combined power of 28.6 kW can be achieved. 相似文献
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大气激光通信机的光学模型和物理实现研究 总被引:1,自引:0,他引:1
将光学理论应用到大气激光通信机设计中,提炼出大气激光通信机的发射和探测过程的光学理论模型,提炼推证了半导体激光器远场发射、准直发射和接收透镜探测损耗的公式,提炼推证了准直激光焦面探测爱里斑公式及对应的质心运算和质心评价公式。设计了和上述推证相关的光学天线和分光镜等。设计了光学天线分辨率、CCD捕获分辨率、通信分辨率、伺服系统分辨率等和系统精度相关的参数。 相似文献
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本文介绍了机动车尾气遥感监测的物理原理,并详细阐述了可调二极管激光吸收光谱学技术,以及在调制过程中的二次谐波调制技术.随后介绍了基于可调二极管激光器的机动车尾气遥感监测系统,剖析了技术难点和解决方法. 相似文献
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自触发脉冲激光测距飞行时间测量研究 总被引:1,自引:0,他引:1
提出一种新型脉冲激光测距方法——自触发脉冲飞行时间激光测距方法。运用该方法有效解决了传统脉冲激光测距法中存在的提高测量精度和缩短测量时间两者之间的矛盾。对该方法及本质特点进行了详细描述和理论分析,并给出用于描述该方法的基本方程。其飞行时间测量系统的设计很大程度上决定了自触发脉冲激光测距的测量精度和测量速度。设计并实现了基于CPLD的自触发脉冲激光测距飞行时间测量系统。CPLD的使用提高了测量精度,并且结构简单,体积小,可靠性高,非常适合高性能便携式的激光测距仪。 相似文献
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调频连续波(FMCW)激光引信具有定距精确度高,抗电磁干扰能力强等优点,但激光探测器易受云层、烟雾和雨雪的干扰,影响引信对目标识别。为此提出了一种FMCW激光与无线电复合探测技术,可有效地解决激光探测技术抗云层、烟雾、雨雪干扰的问题。在分析FMCW激光探测技术与FMCW无线电探测技术的工作原理基础上,给出了激光无线电复合探测方案,并验证了系统的可行性。 相似文献