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Jyi-Lai Shen 《International Journal of Infrared and Millimeter Waves》2006,27(5):753-766
In this paper, we have successfully developed a new low coherence pulsed Doppler lidar concept for wind speed measurements,
in which a pulsed laser is used as the source for measurement and reference beam. A fraction of the transmitted pulse is stored
in a fiber optic ring resonator with a path length longer than the pulse. The output of the resonator is a pulse train that
is used as the reference beam and can be mixed with the Doppler shifted measurement signal. Because this reference has traveled
a distance equivalent to the measurement beam’s path length, low coherence sources can be used. Inserting an erbium-doped
fiber amplifier into the resonator ensures that the stored pulses do not decay in amplitude. Careful control of gain and amplified
spontaneous emission is required to prevent laser oscillation while maintaining sufficient gain for the signal. Experiments
prove that 16 reference pulses of sufficient amplitude and stability can be generated. Computer simulations suggest that 70
pulses should be achievable, which would be equivalent to a Doppler lidar measurement range of 2,550 m. 相似文献
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An 8 × 10 Gbps direct light-to-logic converter for hybrid mounted Ge photodiodes is presented. The receiver is realized in standard 0.35 μm SiGe BiCMOS technology and the Ge photodetector is directly mounted on the top of the CMOS wafer. Each of the 8 channels includes a transimpedance amplifier, limiting amplifier stages and a 50 Ω CML output driver. The overall transimpedance is 275 kΩ and at a data rate of 10 Gpbs a sensitivity of − 23.1 dBm (BER = 10−9) is reached. 相似文献
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提出了一种基于高掺杂硅酸盐增益光纤、输出波长为1 064nm的超短腔单频光纤激光器.该单频光纤激光器采用分布布拉格反射式腔型结构,有效腔长为2cm,其增益介质为1.1cm长的高浓度掺Yb3+光纤.通过恰当的温度控制,获得了线宽为4.8kHz的稳定单频激光输出.当注入泵浦光为378mW时,输出功率为13mW,斜效率为3.4%.在频率大于1 MHz时,测得该光纤激光器的相对噪声强度值约为-132dB/Hz.采用主振荡功率放大结构,对该单频光纤激光器的输出功率进行放大.当放大增益光纤长度选取为56cm时,得到了325mW的最大输出功率,其斜效率为52.8%. 相似文献
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线性化器是毫米波通信系统中的关键器件,在改善放大器的线性指标及提高通信质量等方面起着至关重要的作用。现阶段国内行波管放大器(TWTA)线性化技术尚不完善,无法满足通信技术发展的应用需求,因此线性化技术的研究刻不容缓。本文提出了一种新的宽频带模拟预失真线性化器结构,用来改善Ka波段TWTA的非线性特性。仿真结果表明,在26~30 GHz频率范围内,输入功率为−20~10 dBm,线性化器的增益扩张≥5.08 dB,相位扩张≥64.81 °。将线性化器与TWTA进行级联测试,中心频率的增益压缩≤3.12 dB,相位压缩≤2.31 °,三阶互调(IMD3)显著提高。 相似文献
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通过分析基于L-C耦合跨阻运放电路的散粒噪声探测器噪声来源,提出了电感的寄生电容对电子学噪声影响的分析模型,并进行了实验验证.研究表明,电感的寄生电容会增大跨阻运放的输入电压噪声增益,从而增加探测器的电子学噪声.当总电感值为1mH时,选用两个0.5mH的电感串联结构相比选用单个1mH的电感,探测器电子学噪声明显降低.由于电感的自共振频率越低,寄生电容越大,选用高自共振频率的电感有助于进一步降低电子学噪声.实验测量得到,在2.5 MHz分析频率处,选用两个0.5mH、自共振频率为6 MHz的电感串联相比选用单个1mH、自共振频率为1.6 MHz的电感,电子学噪声的降低了3dB.在相同入射激光条件下,该改进模型可以有效提高探测器的信噪比. 相似文献
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