【作者】 尹国路；

【导师】 娄淑琴；

【作者基本信息】 北京交通大学 ， 电子科学与技术， 2013， 博士

【摘要】 伴随着光纤通信技术系统需求的日益提高,光纤激光器和光纤传感器性能的进一步提高,已成为近年来的一个持续研究热点。在国家自然科学基金项目和中央高校基本科研业务费项目的资助下,本学位论文针对基于瑞利背向散射、双芯光纤、拉锥光纤、偏心熔接以及倾斜长周期光纤的多种光纤滤波器开展了深入的理论和实验研究,并以此为基础,提出了新型可调谐单纵模激光器、多波长单纵模激光器、波长间隔连续可调谐双波长光纤激光器、可调谐多波长激光器和可调谐窄线宽光纤激光器,以及大测量范围、高灵敏度的折射率传感器和弯曲传感器。论文取得的主要创新性成果如下：1.提出基于单模光纤瑞利背向散射(Rayleigh backscattering, RBS)的单纵模光纤激光器。采用主腔和RBS反馈共享的单腔激光器结构,利用660m单模光纤和可调谐带宽为0.5nm的滤波器,首次实现了线宽2.5-3.0kHz、边模抑制比72dB、阈值泵浦功率30mW、7个可调谐波长的单纵模掺铒激光输出。此外,采用光纤布拉格光栅级联和半导体放大器改进的激光器结构,首次实现了基于RBS的多波长单纵模光纤激光器。2.提出基于双芯光纤耦合器型(TCF-Coupler)滤波器的波长间隔连续可调的双波长激光器。采用双芯光纤长度为1.1m的TCF-Coupler滤波器,实现了波长间隔连续可调谐范围0.1-1.2nm、边模抑制比40-52dB、功率波动低于0.25dB、波长漂移约为0.004nm、室温下稳定的双波长激光输出。同时,采用长度为86.85mm、自由谱宽为49nm的TCF-Coupler滤波器,实现了测量弯曲率范围0-9.3m-1、最大灵敏度-14.7nm/m"1的宽范围、高灵敏度的弯曲传感。3.提出基于双芯光纤马赫增德尔干涉仪型(TCF-MZI)滤波器的多波长光纤激光器。采用双芯光纤长度为1.5m的TCF-MZI滤波器,以6m和2m掺铒光纤,分别在1560nm和1530nm波段实现了基于非线性光学环镜(NOLM环)激光器结构的多波长激光输出,输出激光波长分别达到40个和30个,对应信噪比分别为28dB和20dB。在此工作的基础上,采用干涉臂长度差为4nm的标准马赫增德尔干涉仪(MZI)和双芯光纤长度为11.5cm的TCF-Coupler构成的复合滤波器,首次实现了基于NOLM环的可调谐多波长激光器,可调谐范围覆盖从1542nm到1566nm的24nm光谱宽度,激光波长数量为19个,波长间隔0.4nm,信噪比为39dB,波长漂移低于0.04nm,功率波动低于±0.3dB。4.提出基于双拉锥光纤马赫-增德尔干涉仪型(TT-MZI)滤波器的可调谐掺铒光纤激光器。采用拉锥光纤束腰直径为49μm、臂长为1m TT-MZI滤波器,在深入研究拉锥光纤束腰直径对激光器边模抑制比、线宽、可调谐范围和可调步长影响的基础上,实现了波长可调谐范围16.1nm、可调步长0.07-0.5nm、线宽10pm、边模抑制比40-50dB、61个激射波长的可调谐激光输出。与其它基于拉锥光纤的可调谐激光器相比较,在实现较大可调谐范围和较高边摸抑制比的同时,极大地缩小了可调步长,增大了激射波长数量。5.研制出基于拉锥光纤和偏心熔接的非对称马赫-增德尔干涉仪(TC-AMZI),削弱了损耗峰从“蓝移”到“红移”的跳变情况,为宽范围折射率连续测量提供了一种有效的解决方案。采用干涉仪长度L=30mm和50mm的TC-AMZI滤波器,实现了灵敏度分别为28.2nm/RIU和59.2nm/RIU的折射率传感。该灵敏度分别是干涉仪长度L=30mm和50mm的TT-MZI滤波器的2倍和3倍。6.采用全矢量复耦合模理论分析了倾斜长周期光纤光栅的模式耦合特性。系统研究了LP1m简并模式TE0m、TM0m和HE2m与纤芯基模的偏振耦合。数值计算结果表明,纤芯基模与LP11m包层模的最大耦合强度发生在倾斜角87。附近,与非倾斜长周期光纤光栅相比,倾斜长周期光纤光栅的透射谱出现了对应于LP1m包层模式的新谐振峰。新谐振峰的位置和强度受输入光偏振态的影响,较传统LP0m模式对应的谐振峰具有更高的折射率传感灵敏度。该特征使倾斜长周期光纤光栅在化学和生物传感领域具有非常重要的潜在应用价值。更多还原

【Abstract】 With the advance of the optical fiber communication technology, fiber laser and fiber sensor with high performance have become the focus in the recent years. Fiber filters play an important role in the development of the novel fiber laser and fiber sensor with high performance. Supported by National Nature Science Fundation Program and Funamental Research Funds for the Central Universities, this dissertation mainly focus on the theoretical and experimental investigations on the fiber filters based on Rayleigh backscattering(RBS), twin core fiber(TCF), taper, core-offset splice, and tilted long period fiber grating(TLPG). Employing these novel filters, we proposed and experimentally demonstrated the tunable single longitudibal mode(SLM) fiber laser, multi-wavelength SLM fiber laser, dual-wavelength fiber laser, tunable multiwavelength fiber alser, tunabel narrow linewidth fiber laser, high sensitive refractive index sensor, and high sensitive bending sensor with wide measuring range.The main innovative achievements of the dissertation are listed below:1. A novel sinlge longitudinal mode fiber laser (SLM-FL) has been proposed and experimentally demonstrated based on RBS in single mode fiber (SMF-RBS). With the establishing of the therotical model of SLM operation based on SMF-RBS, a single laser cavity was formed by the structure of sharing light path of main cavity and the RBS feedback cavity. Utilizing the RBS in660m SMF and the tunable filter with tunable bandwidth of0.5nm, the SLM-FL can operate at7wavelengths with linewidth of2.5-3.0kHz, side mode suppression ratio (SMSR) of72dB, and threshold power of30mW. Futuremore, muli-wavelength SLM laser based on SMF-RBS have been proposed and experimentally demonstrated by using the structure with cascaded fiber Bragg gratings and semiconductor optical amplifier.2. A stable dual-wavelength Er-doped fiber laser (EDFL) with continuously tunable wavelength spacing was proposed and experimentally demonstrated by using a TCF coupler (TCF-Coupler) filter at room temperature. By using a1.1m TCF-Coupler filter, The wavelength spacing of the dual-wavelength laser was continuously tuned from0.1nm to1.2nm with a with a SMSR of40-50dB, power fluctuation of0.25dB, and wavelength drift of0.004nm. A further application of the TCF-Coupler filter in curvature sensor was investigated. By utilizing a TCF-Coupler filter with length of1.1m and free spectral range of49nm, a high sensitive fiber cuvature sensor with the wide measuring range can be achieved. Its sensitivity can reach to-14.7nm/m-1and the curvature range can be measured from0to9.30m-1.3. A multiwavelength fiber laser based on nonlinear optical loop mirror (NOLM) was proposed and experimental demonstrated by using a twin core fiber-based Mach-Zehnder interferometer (TCF-MZI).40lasing wavelengths with a signal noise ratio (SNR) of28dB can operate around the wavelength of1560nm when the length of EDF is6m. Further more,30lasing wavelengths with a SNR of20dB were achieved around the wavelength of1530nm for the first time when the length of EDF is2m. In order to exptend the range of operation wavelength, a tunable multiwavelength fiber laser based on NOLM was proposed and experimental demonstrated by using a compound filer which cascaded a standard MZI and a TCF-Coupler filer with TCF length of11.5cm,. By utilizing a standard MZI with optical path difference of4mm and a TCF-Coupler filter with length of11.5cm, the lasing waveband can been linearly tuned over a rang of-24nm form1542nm to1566nm with a channel spacing of0.4nm, a SNR of39dB, a wavelength drift of0.04nm and a power fluctuation of±0.3dB.4. A tunable fiber laser based on an two-taper Mach-Zehnder interferometer (TT-MZI) filter was realized, and the effect of beam waists of the tapers on performance of the laser was investigated including the SMSR, bandwidth, tunable range, and tunable step. Experimental results show that the tunable laser can cover the wavelength range of16.1nm with tuning steps of0.07-0.5nm, a bandwidth of10pm, and a SMSR of40-50dB by using TT-MZI with arm length of1m and taper beam waist of49nm. Compared with other tunable lasers based on taper, this tunable laser not only obtains a larger tunning range and a higher SMSR, but also decreases the tunning step to increase the wavelength number.5. A novel high sensitive refractive index (RI) sensor was proposed and experimentally demonstrated by using an asymmetrical fiber Mach-Zehnder interferometer based on taper and core-offset splice (TC-AMZI). Experimental results show that the RI sensitivity of the proposed sensor is28.2nm/RIU (refractive index unit) and59.2nm/RIU for arm length of30mm and50mm, respectively, which are2times and3times as large as those of TT-MZI with the same arm length. Meantime, the phenomenon that the attenuation peaks jumped from "blue shift" to "red shift" can be weakened in TC-AMZI. This makes TC-AMZI suitable for the large range RI measurement.6. The mode coupling in TLPG was analyzed by using the full vector complex coupled mode theory. The polarization sensitive coupling betwteen the LP01and LP1m modes was investigated in detail, including degenerate vector modes TEo0m, TM0m and HE2m.Numerical results show that the maximum coupling between LP01and LP1m modes occurs at tilt angle of～87°. Compared with the non-titled LPQ new resonance bands corresponding to the LP1m cladding modes were observed in the transmission spectrum of the TLPG. The wavelength and transmission of the new resonance bands are effected by the the state of polarization (SOP) of the input light. Also, the RI sensitivity of the new resonance wavelength is much higher than that of the normal resonance wavelength corresponding to the LPom cladding modes. Such TLPG would have a number of potential applications in chemical and biological sensing field.更多还原