【作者】 赵铭；

【导师】 申铉国； 郭玉彬；

【作者基本信息】 吉林大学 ， 通信与信息系统， 2008， 博士

【摘要】 1.55μm单纵模光纤激光器在未来高速率光纤通信、高精度光纤传感、军事等领域具有广阔的前景,是很有意义的研究课题。针对单纵模光纤激光器,作者主要完成如下工作:1、推导了三能级光纤激光器的稳态工作特性,分析了Er/Yb系统能级结构及非辐射交叉驰豫过程,优化了光纤激光器的谐振腔结构。2、研究了短腔光纤激光器的谐振腔结构特点,实验优化了Er/Yb双掺光纤的长度,以13cm的短光纤获得了11mW的输出功率。3、采用耦合模式理论,分析了光纤Bragg光栅的原理,研究了光纤光栅的写入方法,并在厘米级Er/Yb双掺光纤上成功地写入一对光纤Bragg光栅。4、以5cm长度Er/Yb双掺光纤直接写入一对FBG作为谐振腔镜,实验研究了光纤激光输出特性、模式特性、及噪声特性,获得了稳定的单纵模激光输出。5、设计了新型光纤激光阵列结构,进行了实验研究,得到了初步的实验结果。6、采用12.5Gb/s高速外调制短腔单纵模Er/Yb双掺光纤激光器,进行21km传输实验,测量了发送、接收光眼图及误码率,得到了性能稳定的传输效果,并对实验结果进行了分析。7、分析了交叉敏感的物理机制,推导了应变和温度同时测量的矩阵方程。利用数值计算仿真光纤传感线形矩阵同时测量应变和温度变化。更多还原

【Abstract】 The works in this thesis are on the basis of two projects: New Single Longitudinal-mode Laser Array Source in WDM All Optical Communications funded by Science and Technology Development of Jilin Province, China. Single longitudinal-mode fiber laser adopts short erbium/ ytterbium codoped fiber (EYDF) as gain medium, it is of high coupling efficiency, low noise, and single longitudinal-mode stability. This kind of fiber laser is one of the most attractile light source in high speed optical communications and high accuracy optical sensor. It is significance to research on the single longitudinal-mode fiber laser for the development of the high speed all optical communications and high accuracy optical sensing.This works mainly focuses on the single longitudinal-mode and high-speed modulation in the 1.55μm fiber laser in order to meet the requirements of modern telecommunication. We develop the single longitudinal-mode short cavity fiber laser according to communications demand as the aim. In this paper, the characteristics of the mode, the fiber Bragg gratings in the high concentration Er/Yb fiber, fiber laser array, and high-speed modulation have been studied experimentally and theoretically, which include:1. The three energy level stabilization characteristic of the fiber laser is deduced and the cavity configuration of the fiber is optimized.2. The single longitudinal-mode operation is realized by a short Er/Yb codoped as resonant cavity pumped by 980nm laser diode (LD). Two fiber Bragg gratings are written in the Er/Yb codoped fiber directly.3. The resonant cavity characteristics of the short cavity fiber laser are studied. The length of Er/Yb co-doped fiber is optimized, and 11mW output power is obtained by using 13cm Er/Yb co-doped fiber as resonant cavity.4. The longitudinal-mode is observed by the interferometer with free spectrum range (FSR) of 7.5GHz and the single longitudinal-mode is approved.5. A fiber laser array is experimented which two short cavity single longitudinal-mode fiber laser are pumped by a LD and the wavelength spacing is 0.8nm. This kind of the fiber laser array can be used in WDM systems and distributed fiber sensing.6. The high-speed rates, 10Gb/s and 12.5Gb/s, are used in the modulation experiment of single longitudinal-mode fiber laser. The eye diagrams of optical transmission and reception are measured by an optical sampling broadband oscilloscope, the transmission performance with high-speed modulation is perfect.7. In addition, the cross-sensitivity between strain and temperautre in the fiber sensor is studied. Then we described the physical mechanics of the cross-sensitivity in fiber sensor and the cross-sensitivity coefficient is obtained.The measurement matrix of the strain and temperature simultaneously are deduced. With highly elliptical core two-mode fiber and double wavelength single detecting the change of strain and temperature simultaneously, the cross-sensitivity can be solved. The relationship of the strain (and temperature) against the two wave phases shifts and Bragg wavelengths are showed. The feasibility of using this type of embedded sensors configuration for simultaneous strain and temperature measurements was demonstrated.With the experimental and theoretical analysis, there are some novel findings in the key technology and its application to fiber lasers in this paper as follows:1. Two fiber Bragg gratings are written in the short Er/Yb co-doped fiber directly and the short cavity is relized. The processing technology of writing gratings on short Er/Yb do-doped fiber is very difficult. 2. Two resonant cavitis are pumped by a 980nm LD simultaneously, and the fiber laser array is realized. The fiber laser array will be applied in the WDM systems, distributed fiber sensing systems and microwave source.3. For the first time the fiber laser is experimented in the high-speed electro-optical externally modulated transmission tests, and the results according with optical communications requirements are achieved through 21km transmission of signal. This system employed NRZ format, LiNbO3 electro-optic modulator, modulation rate from 10Gb/s to 12.5Gb/s. The signal eye diagrams of the multi-rate transmission and reception are measured, and the eyelids are thin. The results show that the coding jam and signal aberrance were not observed and signal-to-noise ratio for better. The high-speed transmission error rate is 10-12, and the system has run error free continuously for 24 hours.The single longitudinal-mode fiber laser in this paper can emit single longitudinal-mode laser, with low noise, no chirp with high-speed modulation, and the laser couples with optical system efficiently, small size array, low cost. This product will be the most potential carrier sources in the new generation all optical communication systems.更多还原