【作者】 冯素春；

【导师】 简水生；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2010， 博士

【摘要】 光纤激光器在密集波分复用系统、光时分复用系统、光载无线通信系统、超高精度长距离光纤传感网络、相干光通信等领域具有广泛的应用前景。本文结合国家自然科学基金及国家863计划项目,针对光通信波段连续波多波长光纤激光器以及单纵模窄线宽光纤激光器的结构及参量优化,进行了一系列的理论及实验研究,取得的主要创新成果如下：1.提出了一种基于保偏光纤光栅的线形腔可切换双波长掺铒光纤激光器,在保偏光敏掺铒光纤两端直接写入光纤光栅,构成无光纤熔接点的全保偏一体化谐振腔,利用掺铒光纤中的偏振烧孔效应,实现了室温下稳定的可切换双波长单偏振掺铒光纤激光器,对基于偏振烧孔效应的可切换双波长光纤激光器的形成机理给出了合理的解释。进一步利用这一原理,提出了基于保偏光纤光栅的对称线形腔多波长掺铒光纤激光器,谐振腔由全光纤Sagnac环镜的两个输出臂各自连接一个保偏光纤光栅构成,实现了室温下稳定的四波长激光输出。还提出了两种基于保偏光纤光栅的环形腔多波长掺铒光纤激光器,利用全光纤Sagnac干涉仪替代光环形器,结合单个以及接续的保偏光纤光栅分别实现了室温下稳定的可切换双波长激光和可切换四波长激光输出。2.提出了一种基于紧凑型全光纤Mach-Zehnder干涉仪的可切换多波长掺铒光纤激光器,用双芯光纤和普通单模光纤构成紧凑型全光纤Mach-Zehnder干涉仪,测试了它的温度以及纵向应力特性,并利用其作为多波长滤波器件,实现了室温下可切换的三波长激光稳定输出,讨论了光纤激光器的形成机理。3.由半导体光放大器作为增益介质,利用保偏光纤光栅作为波长选择器件,在三种不同的激光器结构上均实现了稳定的可切换双波长光纤激光器,并比较和分析了以半导体光放大器与以掺铒光纤放大器为增益介质的光纤激光器的不同之处。另外,以取样光纤光栅以及啁啾莫尔光纤光栅两种特殊结构光纤光栅作为多波长滤波器件,分别实现了室温下稳定的四波长激光和三波长激光输出。4.提出了一种将三个光纤光栅直接写入光敏掺铒光纤中形成非对称双腔的单纵模掺铒光纤激光器,非对称双腔扩大了纵模模式间隔,而且腔内不存在光纤熔接点,降低了腔内损耗,实现了线宽约5kHz的单纵模激光输出,为长距离光纤传感系统提供了窄谱线的高效光源。5.提出了两种双波长单纵模掺铒光纤激光器,将保偏光纤光栅作为波长选择器件,利用偏振烧孔效应,采用未泵浦的掺铒光纤作为饱和吸收体以及光纤反馈环对激光纵模进行选择,分别实现了环形腔和线形腔结构的可切换双波长单纵模掺铒光纤激光器。更多还原

【Abstract】 Fiber lasers have attracted much interest because of their potential applications in wavelength division multiplexed fiber communication systems, optical time division multiplexed fiber communication systems, radio over fiber communication systems, long distance optical fiber sensing systems with ultra-high resolution, coherent optical communication and so on. Under the supports of national 863 high technology program and national nature science foundation, this thesis is devoted to design and optimize the structure of the multi-wavelength fiber lasers and narrow linewidth single longitudinal mode fiber lasers, mainly including proposing and optimizing the structures of fiber lasers and deeply investigating the characteristics of fiber lasers. And the main achievements of this thesis are listed as follows:1. A stable and single-polarization, switchable dual-wavelength erbium doped fiber laser at room temperature with two polarization maintaining fiber Bragg gratings directly written in a polarization maintaining and photosensitive erbium doped fiber is presented and experimentally demonstrated. The working principle of the fiber laser which is based on the polarization hole burning is also analysed. Furthermore, a multi-wavelength erbium doped fiber laser using two polarization maintaining fiber Bragg gratings in the symmetrical linear cavities at room temperature is also experimentally realized. The laser cavity is composed by the Sagnac loop mirror connected with two polarization maintaining fiber Bragg gratings, and stable four-wavelength lasing emission can be generated at room temperature. Moreover, two kinds of multi-wavelength erbium doped fiber ring laser at room temperature are proposed and experimentally demonstrated. With the removal of the optical circulator, switchable dual-wavelength lasing outputs are achieved based on the use of one polarization maintaining fiber Bragg grating within a Sagnac loop interferometer as the wavelength-selective filter. Switchable four-wavelength lasing outputs are also obtained with cascaded polarization maintaining fiber Bragg grating within a Sagnac loop interferometer.2. A switchable multi-wavelength erbium doped fiber ring laser based on a compact in-fiber Mach-Zehnder interferometer comb filter at room temperature is presented. The comb filter is formed by splicing a section of twin-core fiber between two single mode fibers. The temperature and strain characteristics of the comb filter are experimentally investigated. The laser can be made to operate in stable single-, dual-and three-wavelength lasing states. Some interesting phenomena are observed and discussed.3. Switchable dual-wavelength fiber lasers based on a polarization maintaining fiber Bragg grating and a semiconductor optical amplifier in three different laser configurations at room temperature are proposed and experimentally demonstrated. The difference between the EDFA-based fiber laser and the SOA-based fiber laser are discussed and analysed. Moreover, multi-wavelength fiber ring lasers based on the semiconductor optical amplifier with sampled fiber Bragg grating and chirped moire fiber Bragg grating as the wavelength-selective filter are proposed. Stable four-wavelength lasing and triple-wavelength lasing have been stably generated, respectively.4. A single longitudinal mode erbium doped fiber laser with asymmetric two cavities is proposed and experimentally realized. It consists of three FBGs directly written in a photosensitive erbium doped fiber to form asymmetric two cavities, which can effectively increase the longitudinal mode spacing. The fiber laser has no intra-cavity fusion splices, and the single longitudinal mode operation with linewidth of less than 5-kHz is confirmed, which provide a highly-efficient narrow-linewidth fiber laser source for long distance optical fiber sensing systems.5. Switchable single longitudinal mode dual-wavelength erbium doped fiber lasers with linear and ring cavities using the polarization maintaining fiber Bragg grating as the wavelength-selective filter are demonstrated, respectively, which are mainly based on the polarization hole burning effect. The stable single longitudinal mode operation is guaranteed by the feedback fiber loop and unpumped erbium doped fiber as the saturable absorber.更多还原