共查询到20条相似文献,搜索用时 15 毫秒
1.
Charge-Pump Phase-Lock Loops 总被引:1,自引:0,他引:1
Phase/frequency detectors deliver output in the form of three-state, digital logic. Charge pumps are utilized to convert the timed logic levels into analog quantities for controlling the locked oscillators. This paper analyzes typical charge-pump circuits, identifies salient features, and provides equations and graphs for the design engineer. 相似文献
2.
A phase-lock loop occasionally will take a long time to settle to equilibrium. Phase dwells at a large error for a prolonged interval. This phenomenon has been dubbed "hangup." The periodic nature of phase detectors is responsible for hangup, which occurs near the reverse-slope, unstable null. Restoring force is small in the vicinity of the reverse null, and noise causes the loop to equivocate about the null. Hangup is very troublesome when fast acquistion is needed with high reliability. One example is synchronization of digital communications. Hangups can be avoided if a large restoring force is applied for large phase errors and if equivocation is prevented. An implementation of an antihangup circuit is proposed. 相似文献
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实现了基于单偏振半导体光放大器高速扫频光源的光相干层析系统。系统中的扫频光源使用偏振相关的半导体光放大器, 采用傅里叶域锁模结构。偏振相关的半导体光放大器有着增益谱宽大、输出功率高的优点, 使得光源仅使用一个放大器即可获得足够的增益谱宽与输出功率。扫频光源输出功率达到32mW左右, 有效扫描频率为45kHz, 输出光谱的中心波长为1326nm, 光谱宽度为115nm。利用系统进行光相干层析成像时, 横向分辨率为9μm, 纵向分辨率为12.9μm左右, 灵敏度为105dB。利用该系统实现了多种生物和非生物样品的光学相干层析成像。 相似文献
4.
实现了基于单偏振半导体光放大器高速扫频光源的光相干层析系统。系统中的扫频光源使用偏振相关的半导体光放大器,采用傅里叶域锁模结构。偏振相关的半导体光放大器有着增益谱宽大、输出功率高的优点,使得光源仅使用一个放大器即可获得足够的增益谱宽与输出功率。扫频光源输出功率达到32mW左右,有效扫描频率为45kHz,输出光谱的中心波长为1 326nm,光谱宽度为115nm。利用系统进行光相干层析成像时,横向分辨率为9μm,纵向分辨率为12.9μm左右,灵敏度为105dB。利用该系统实现了多种生物和非生物样品的光学相干层析成像。 相似文献
5.
The analysis, and design of third-order, (and higher) phase-locked loops (PLL) is difficult. This paper presents a novel approach to overcome these difficulties by allowing high-order loops to be viewed as a natural extension of lower order ones. This is accomplished by adding nested first-order feedback loops around a basic first-order loop filter. Our approach will also be related to the concept of PLLs with aided acquisition. The model presented has been implemented and tested in Simulink 相似文献
6.
The optical noninvasive diagnostic of characteristic of silicon semiconductor de-vices by using a InGaAsP/InP semiconductor laser as an optical probe is reported.The princi-ple of experimental method is based on the dependence of the optical refractive index on the carrier charge density in the active region of devices and detection of variation of refractive index by two laser beam interferometric techniques. 相似文献
7.
《Photonics Technology Letters, IEEE》2009,21(11):733-735
8.
Satyan N. Wei Liang Aflatouni F. Yariv A. Kewitsch A. Rakuljic G. Hashemi H. 《Photonics Technology Letters, IEEE》2008,20(11):897-899
In this letter, we demonstrate the use of an electronic feedback scheme using a voltage controlled oscillator (VCO) to control the optical phase of individual semiconductor lasers (SCLs) phase locked to a common reference laser using heterodyne optical phase-locked loops (OPLLs). The outputs of two external cavity SCLs phase-locked to a common reference laser are coherently combined, and the variation in the relative optical path lengths of the combining beams is corrected by dynamically changing the phase of the offset radio-frequency signal fed into one of the OPLLs by means of a VCO. A stable power combination efficiency of 94% is achieved. This inherently different method of phase control, i.e., electronic rather than the use of electrooptic crystals, is deemed essential for new applications involving coherent optoelectronics. 相似文献
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Memon Faisal Ahmed Morichetti Francesco Arain Zulfiqar Ali Korai Umair Ahmed Melloni Andrea 《Wireless Personal Communications》2019,106(4):2149-2161
Wireless Personal Communications - In this work, we first analyse the behaviour of semiconductor laser in the presence of weak-to-moderate feedback from a single (lumped) and double external cavity... 相似文献
12.
本文报告了一种具有实用价值的半导体大光腔激光器列阵,介绍了该器件的两种典型结构和基本特征,以及设计思想,制作工艺等.该器件阈值电流为2-4A,峰值功率为75-100瓦,是目前国内列阵器件的最高水平. 相似文献
13.
Thakulsukanant K. Bei Li Memon I. Mezosi G. Zhuoran Wang Sorel M. Siyuan Yu 《Lightwave Technology, Journal of》2009,27(6):631-638
This paper demonstrates an optical node that simultaneous carries out multicast optical switching and all-optical label swapping. While the optical payload is being forwarded by a fast optical switch matrix, the optical label is processed by a semiconductor ring laser (SRL) bistable. Old address bits in the label are erased by optically blocking the switching of the ring laser and new address bits are inserted by modulating the output from SRL directly. This label swapping scheme is the first demonstration of bit-level data processing using the all-optical logic capabilities of a semiconductor ring laser. 相似文献
14.
超短光脉冲的产生是光纤CDMA通信的关键技术之一。本文采用半导体激光器多模速率方程模型,分析了增益开关半导体激光器的输出特性,对激光器的本征参数、工作条件与超光脉冲输出特性的关系进行了探讨:也研究了获得取最佳输出特性的条件,可通过控制偏置电汉来调节光脉宽,且在最佳偏置电汉下对市制电流脉宽有一定的宽容度。 相似文献
15.
高分辨飞秒光学相干断层成像系统 总被引:2,自引:1,他引:1
建立了飞秒激光自由空间光学相干断层成像OCT)系统,给出了该系统的初步实验结果。系统的光源为掺Ti蓝宝石锁模激光器,输出脉宽小于50fs,中心波长为800nm,谱宽约为40nm,飞秒OCT所达到的纵向分辨率为8μm,横向分辨率为7.6μm,并用于飞秒激光微加工样品表面轮廓的检测。 相似文献
16.
光学相干层析成像(OCT)是近年来发展较快的一种新型成像技术,能对生物组织内部的微观结构进行高分辨率的横断面层析成像,具有快速、非侵入及高分辨率等特点,在体生物组织微观结构分析和疾病诊断等方面具有重要的应用价值.综述了采用光学相干层析成像技术确定生物组织光学特性的研究. 相似文献
17.
本文主要介绍用于光纤传输系统的行波半导体激光放大器(TWSLA)。首先描述 TWSLA 的激光器刻面抗反射(AR)涂层的特性,然后描述半导体激光放大器(SLA)的重要特性,如小信号增益、信号增益饱和及噪声特性,最后讨论了 TWSLA 的结构设计。 相似文献
18.
采用半导体光放大器的多波长光纤环形激光器 总被引:1,自引:0,他引:1
报道了一种插入马赫-曾德尔(M-Z)光纤干涉仪的半导体光放大器(SOA)多波长光纤环形激光器,实现了信道间隔为100 GHz的稳定的多波长连续光激射,其输出光谱3 dB带宽为19.5 nm,消光比大于30 dB.其中在17.9 nm范围内获得了22个波长的连续光,功率不平坦度为1.2 dB,总输出功率为5.1 dBm.对该结构的多波长激光器输出光谱宽,不同波长间功率波动小的特性进行了分析,提出在较低环腔损耗下,半导体光放大器的增益饱和及四波混频(FWM)效应的共同作用使环腔内多波长光功率获得自动均衡;并对实验观测到的激光器输出光谱带宽及中心波长随半导体光放大器驱动电流降低或环腔损耗增大而减小的现象进行了讨论. 相似文献
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数值模拟了增益钳制SOA(GC-SOA)的波长转换过程,分析了GC-SOA实现波长转换的原理.首次发现了GC-SOA波长转换中类似接通延迟的现象,这种现象将限制GC-SOA在高速波长转换中的应用. 相似文献
20.
We report on the experimental demonstration of optical single sideband (SSB) modulation using a directly modulated semiconductor laser under strong optical injection-locking. Modulation sidebands with 15-dB power ratio between the lower and upper sidebands have been achieved. The longer wavelength sideband is resonantly amplified by the injection-locked laser cavity mode. The radio-frequency performance of the optical SSB after 80-km fiber transmission is significantly improved compared with a typical symmetric sideband modulation of a free-running laser. A 622-Mb/s data transmission on a 20-GHz subcarrier is demonstrated over an 80-km fiber link. 相似文献