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本文报道了用锁模磷酸盐玻璃激光的倍频光泵浦若丹明B超短腔染料激光器的实验装置和实验结果,用TPF和OSA的组合装置研究了磷酸盐玻璃激光器的最佳运转条件,得到了脉宽~5ps的锁模脉冲系列,以此ps光源泵浦的染料激光器获得了波长为620.1~641.6nm,脉冲宽度小于4ps的单模可调谐激光输出。 相似文献
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中国科学院上海光机所制成一种新型可调谐染料激光器.这台激光器采用Nd~(3+):YAG倍频激光和三倍频激光泵浦,用微机控制由光栅和棱镜组成的调谐系统,自动调谐激光器的输出波长,并同时自动显示激光波长.连续调谐范围复盖着整个可见光区(波长从0.42μm至0.71μm),激光脉冲宽度在30~50ps之间,平均功率大于2mW,峰值脉冲 相似文献
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利用啁啾脉冲增益饱和放大特性,搭建了一台基于泵浦分束结构的波长可调谐1μm全保偏光纤超短脉冲激光器。该激光器由超短脉冲激光振荡器和超短脉冲激光放大器组成,控制注入到放大器的啁啾脉冲能量,使放大器处于增益饱和或非饱和状态,从而实现激光中心波长的精确调节。实验中,激光器可产生1030.0~1034.5 nm波长可调谐的超短脉冲激光,光谱带宽大于13.1 nm。在整个波长调谐范围内,放大脉冲激光的信噪比均大于55 dB,时域脉宽为7.1~7.5 ps。此外,得益于全保偏光纤架构,该1μm超短脉冲光源表现出良好的长期稳定性,平均功率的相对抖动低至0.1%。该激光器产生的波长可调谐超短脉冲激光,能够精准匹配Yb∶YAG、Yb∶CaF2、Yb∶Lu2O3等晶体的发射峰,可为后续Yb∶YAG、Yb∶CaF2、Yb∶Lu2O3等大能量超短脉冲固体激光器提供紧凑、便捷、稳定的种子光源。 相似文献
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光电流光谱学的原理基于激光感生电流效应.即它是在低压气体或各种金属蒸气中维持恒定的直流放电或脉冲放电的条件下,用可调谐激光器激发放电样品,当激光波长调谐到与放电样品的原子(或分子)跃迁频率时,放电样品的阻抗就发生变化,使回路电流发生相应的变化.用锁相放大器或灵敏示波器对这种变化的信号进行测量.本实验装置由氮分子激光器泵浦的可调谐染料激光器激发样品,波长由光谱仪标定.图1为实验装置示意图.染料激光器采用20倍的扩孔望远镜和每毫米1200条刻线的光栅进行波长调谐,染料用若丹明6G并溶于乙醇中.激光调谐范围从5800 相似文献
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氙灯泵浦的可调谐染料激光器锁模脉冲用XeCl准分子激光器泵浦的三级染料激光放大器放大后,经倍频再用XeCl准分子激光器放大,在308毫微米处获得了微微秒高功率激光脉冲输出,其峰值功率可达500兆瓦,功率净增益为200。 相似文献
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友清 《激光与光电子学进展》1997,34(3):5-7
虽然掺钛蓝宝石激光器提供可调谐红外输出,但用脉冲激光器产生可调谐输出,历来属染料激光器的范畴。最近光参量振荡器已成为引人注目的光源,它使调谐范围扩大,使用也较容易。对染料和钛蓝宝石激光器以及多数商业化光参量振荡器,基频调谐范围扩大到可见和近红外光谱区。但许多用户要求输出进一步扩大到紫外和红外区。最直接满足这种要求的技术是以非线性过程为基础。不管是通过倍频、三倍频和和频达到200nm以下,还是通过差频达到1.5μm以上,这些固体频率转换技术都可产生令人振奋的实验结果。激光器产生一系列脉冲宽度和连续波输出。… 相似文献
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Low complexity affine MMSE detector for iterative detection-decoding MIMO OFDM systems 总被引:1,自引:0,他引:1
Iterative turbo processing between detection and decoding shows near-capacity performance on a multiple-antenna system. Combining iterative processing with optimum front-end detection is particularly challenging because the front-end maximum a posteriori (MAP) algorithm has a computational complexity that is exponential. Sub-optimum detector such as the soft interference cancellation linear minimum mean square error (SIC-LMMSE) detector with near front-end MAP performance has been proposed in the literature. The asymptotic computational complexity of SIC-LMMSE is O(nt 2nr + ntnr 3 + ntMc2Mc) per detection-decoding cycle where nt is number of transmit antenna, nr is number of receive antenna, and Mc is modulation size. A lower complexity detector is the hard interference cancellation LMMSE (HIC-LMMSE) detector. HIC-LMMSE has asymptotic complexity of O(nt 2nr + ntMc2Mc) but suffers extra performance degradation. In this paper, two front-end detection algorithms are introduced that not only achieve asymptotic computational complexity of O(nt 2nr + ntnr 2 [Gamma (beta) + 1] + ntMc2Mc) where Gamma(beta) is a function with discrete output {-1, 2, 3, ...,nt} and O(ntMc2Mc) respectively. Simulation results demonstrate that the proposed low complexity detection algorithms offer exactly same performance as their full complexity counterpart in an iterative receiver while being computational more efficient. 相似文献
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We consider the transmission of K binary phase-shift keying signals over M diversity channels through a rich scattering environment. Improved group detection rules are proposed to mitigate the effect of the improper multiaccess interference, and an enhancement of the system receive diversity order is shown to be obtained. For example, it is demonstrated that a further gain of |g~|/2 per group is obtained compared with conventional group detection, where |g~| is the interfering group size. In addition, when there is only one antenna per group, the considered receiver with the improved detection rules is equivalent to the decorrelator. In this case, it is shown that (K-1) interferers can be ed out, and that an M-(K-1/2) receive diversity order is achieved, compared with only M-/sup 2/K+1 with the conventional detection rules. Numerical results will further put in evidence such gains. 相似文献
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The tone sense multiaccess with partial collision detection (TSMA/PCD) protocol is particularly suitable for a packet satellite system serving an area with a dense population of earth stations. By incorporating a narrowband ground radio channel for broadcasting busy ones, the earth stations are able to avoid packet collisions by sensing for the absence of busy tones before transmitting packets. Partial collision detection capability can also be achieved. Single-tone TSMA/PCD gives 97% of the carrier-sense multiaccess with collision detection (CSMA/CD) throughput when N =10 tones are used, while for multitone and slot-by-slot announcement TSMA/PCD protocols only N =8 and N =2, respectively, are sufficient to drive the system to the CSMA/CD performance 相似文献
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A generalized quadrature-quadrature phase shift keying (Q2 PSK) signaling format is considered for differential encoding and differential detection. Performance in the presence of additive white Gaussian noise (AWGN) is analyzed. Symbol error rate is found to be approximately twice the symbol error rate in a quaternary DPSK system operating at the same E b/N 0. However, the bandwidth efficiency of differential Q2PSK is substantially higher than that of quaternary DPSK. In differential detection, it is quite reasonable to suspect that errors tend to occur in pairs. It is shown that when the error is due to AWGN, the ratio of double error rate to single error rate can be very high, and the ratio may approach zero at high signal-to-noise ratio. In an attempt to improve the error rate performance, differential detection through maximum-likelihood decoding based on multiple or N symbol observations is considered 相似文献
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石英增强光声光谱在氢气纯度分析中的应用 总被引:1,自引:0,他引:1
设计了一种基于石英增强光声光谱技术的痕量气体传感器,用来检测非纯氢气中的痕量甲烷浓度。传感器被配置了一个微型谐振腔,能够在空间上对声波进行限制,用以增强信号幅值。在这种配置和27 kPa的最优气压下,获得的甲烷探测灵敏度为3.2 ppm(1 s平均时间),相应的归一化噪声等效吸收系数(1σ)为2.45×10-8cm-1W/Hz1/2。 相似文献
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Xiupu Zhang Peixuan Jiang 《Lightwave Technology, Journal of》1992,10(8):1127-1131
The performance of a coherent optical M -ary continuous-phase frequency-shift-keying (CPFSK) receiver using limiter-discriminator (L-D) detection is investigated. It is shown that L-D detection of CPFSK optical signals offers the best performance for a large normalized IF beat spectral linewidth, ΔνT . When the modulation index is unity, the receiver is immune to laser phase noise and can produce (M /4) exp (-SNR) symbol error probability, which may be considered as the upper bound if the optimal modulation index is used (SNR is the signal-to-noise ratio per symbol). Optimum modulation indexes are 0.8 and 1 at ΔνT =1% and ΔνT =2%, respectively, for M =4, 8, and 16 相似文献
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针对大动态低码率PCM/FM遥测信号的可靠接收问题展开研究,给出了一种基于连续相位调制(CPM)信号原理的载波频偏矫正及差分序列检测的非相干接收方案。针对限幅鉴频、多符号检测及差分序列检测等3种非相干解调算法,介绍了各自应用于PCM/FM信号的算法原理,并比较了3种算法的解调性能及对大动态环境的适应能力。计算机仿真表明,在无残留频偏情况下,2符号相位差分序列检测性能最好;但在0.05倍码速率的残留频偏下,1符号相位差分序列检测的性能更好,优于2符号相位差分序列检测、限幅鉴频检测和多符号非相干检测。对PCM/FM信号的讨论包含了几种典型的非相干解调,对大动态环境下的PCM/FM接收有重要的参考价值。 相似文献
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Barton R.J. Poor H.V. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1990,36(3):485-501
The application of RKHS (reproducing kernel Hilbert space) theory to the problems of robust signal detection and estimation is investigated. It is shown that this approach provides a general and unified framework in which to analyze the problems of L 2 estimation, matched filtering, and quadratic detection in the presence of uncertainties regarding the second-order structure of the random processes involved 相似文献