【作者】 冀青；

【导师】 马秀荣；

【作者基本信息】 天津理工大学 ， 信号与信息处理， 2010， 硕士

【摘要】 随着社会步入信息化时代,人类对通信容量的需求呈现飞速增长的趋势,波分复用(WDM)通信技术应运而生。目前,波分复用通信系统正朝着信道数目越来越多的方向发展。为了降低成本,采用多波长激光器作为通信系统光源成为必由之路。在各类多波长激光器中,多波长光纤激光器以其众多优点成为研究热点。本文以双波长窄线宽环形腔光纤激光器及其应用为研究对象,进行了相关理论及实验研究,完成的工作包括：1.阐述了激光器谐振腔的基本类型,对环形谐振腔的传输特性进行了分析。2.理论分析了具有对称结构的双π相移光纤布喇格光栅的输出特性,在此基础上搭建基于相移光纤光栅的环形腔掺铒光纤激光器,实现了波长间隔为0.076nm的双波长激光输出。对于相移光纤光栅,合理地选择光栅参数,如长度、折射率调制深度等参数可以其具有宽波长间隔、透射阻带以及窄线宽的滤波特性,还可将其应用到光生微波/毫米波系统中可得到更高频率的微波/毫米波信号。3.实验研究了光纤饱和吸收体对激光模式的影响。实验中分别采用长度为1m,2m的高掺杂浓度的掺铒光纤作为饱和吸收体搭建了环形腔掺铒光纤激光器,对饱和吸收体对激光模式的影响进行实验研究。研究结果表明：饱和吸收体对激光模式只是存在一定的衰耗作用,并不能在饱和吸收体内形成窄带滤波器。4.提出一种基于光差拍技术的新型频率合成器实现方案,该频率合成器可实现从DC到上百GHz的梳状谱信号输出。实验利用10GHz光电探测器对一腔长为27米的环形腔掺铒光纤激光器输出的多纵模激光进行差拍,得到频率间隔为7.63MHz的梳状谱信号输出。受光电探测器响应速率的影响梳状信号的频率范围为DC-10GHz。5.提出了一种DBR光纤激光器有效腔长的测量方法,进行了相关理论与实验研究。搭建了DBR光纤激光器,通过测量谐振腔内两个相邻纵模之间的频率间隔,无需知道光栅的精确物理长度,可精确测量DBR光纤激光器的有效腔长。实验测得的结果与已有的理论计算结果符合很好,测量精度可高达10-4mm。更多还原

【Abstract】 With the coming of information era, human society’s increasing demand for communication capacity drives the introduction of Wavelength Division Multiplexing(WDM). In present, the number of signal channels keeps increasing with the development of WDM communication system. Due to their economic cost, it is an indispensable way to utilize multi-wavelength lasers as optical sources in communication system. Multi-wavelength fiber lasers become the research focus for their attracting merits among the different kinds of lasers. This thesis is mainly concentrated on dual-wavelength narrow linewidth fiber ring laser and its application. The main work includes the detail descriptions on the following:1. The fundamental kinds of resonators of fiber laser were introduced. The transmission characteristics of fiber ring resonator were analyzed.2. The transmission spectrum of dual-πphase-shifted fiber Bragg grating with symmetrical structure was analyzed. Based on the theoretical analysis, we proposed a dual-wavelength fiber ring laser with wavelength spacing of 0.076nm using a dual-πphase-shifted FBG. Phase-shifted fiber Bragg grating with wide wavelength-spacing, stopband and narrow-linewidth could be easily realized by properly choosing the parameters of fiber Bragg gratings, and this will benefit the optical generation of microwave/millimeterwave with high frequency.3. The experimental study of saturable absorber’ effect on the modes of laser was carried. An Er3+-doped fiber ring laser was proposed, in which a 1m and 2m Er3+-doped fiber was used as saturable absorber respectively. The experiment results show that the modes of laser were great attenuated by the saturable absorber. The narrow band-pass optical filter can’t be formed in the saturable absorber.4. A scheme of a novel frequency synthesizer based on the optical heterodyne technique was proposed. A 10GHz-photoelectric detector was utilized to detect a multi-longitudinal-mode laser beam which was produced by a multi-longitudinal mode Er3+-doped fiber ring laser with cavity length of 27m, and a series of beating signals with frequency spacing of 7.63MHz were obtained at the output port of the detector. The output frequency was from 0 to 10GHz, which was restricted by the response frequency of the photoelectric detector.5. A novel method for the measurement of the effective cavity length of DBR fiber laser with fiber Bragg grating Fabry-Perot cavity as the resonator was proposed. The effective cavity length of DBR fiber laser was accurately measured by measuring the frequency spacing of two adjacent longitudinal modes in the cavity without the precise physical length of fiber Bragg gratings. The measurement result was in great agreement with the theoretical calculated result. The measurement accuracy was as high as 10-4 mm.更多还原