Study On The Techniques Of Tunable Dual Wavelength Ring Erbium-doped Fiber Laser

Fiber laser has been a focus in the study field for the past few years. It is used in the various domains, such as fiber communication, fiber sensing, military affairs, manufacturing, optical processing, full color display, and the like, due to its wave-guiding structure, admissible heavy pumping, and predominant characteristics of high conversion efficiency, good beam quality, high conversion efficiency, low threshold, narrow line-width, wavelength diversity, good compatibility, simple structure, and so on. Especially, the tunable dual wavelength fiber laser plays an important role in the field of fiber communication system based on WDM (Wavelength Division Multiplex) and fiber sensing. And it provides not only the light source for two signal channels so as to simplify the structure of optical sender, but also the tunable wavelength for the dynamic allocation of optical-fiber network in order to increase network flexibility. So, it is significant to study on it.This dissertation studies on the techniques of tunable dual wavelength ring erbium-doped fiber laser in depth and systematic research. The main content is as follows:To begin with, it briefly introduced the current research of tunable wavelength and multi-wavelength fiber laser, and analyzed the fundamental principle and running characteristic of fiber laser.Second of all, based on the analysis of system composition of fiber laser, this dissertation put forward a scheme to design an experimental system of tunable dual wavelength ring erbium-doped fiber laser, which adopted a Y-type filter, including two FBGs (Fiber Bragg Grating), and used mechanical means tuning them simultaneously to make it output tunable dual wavelength. This system possessed such numerous merits as easy tuning, fast tuning and so forth. And the feasibility of this scheme was analyzed.In the third place, the experimental systems were set up according to the proposal of this dissertation. The characteristics of FBGs were tested by the ASE broad band light source, and then the experiment of tunable single wavelength ring erbium-doped fiber laser was carried out. The testing results of FBGs indicated that there was a good linear relation between the load and the wavelength, during the process of strain, and they were fit for experimental system of tunable fiber laser. And the experimental results of tunable single wavelength fiber laser indicated that this system achieved the goal of outputting tunable wavelength, and the tuning sensitivity and range were obtained.On this basis, the experiment of tunable dual wavelength ring erbium-doped fiber laser was carried out. The experimental results indicated that the two output wavelengths can be tuned at the same time, that is, the two wavelengths can shift towards long wavelength or short wavelength respectively, and the threshold power and the stability of output power were determined severally. And then the results were analyzed, data was processed, and the curves were fitted, including load-wavelength, the difference of load-the difference of wavelength, threshold power and power stability. It can be obtained from the experiment that the tuning sensitivity was 0.1530nm/kg, the tuning range was 0.808nm, the threshold power was 6.557mW, and the stable output power was 1.68mW.Finally, the dissertation achieved the targets of outputting tunable dual wavelength of ring erbium-doped fiber laser, and stable power, after studying on this research subject. However, the tuning range was not the actual one, and the two wavelengths were not too stable, due to the limitation of experimental condition and period. During the following research, on the one hand, the actual range should be determined by increasing the quantity of weight below the allowed band of FBG, and on the other hand, using the method of balancing the loss can make various channels output the same optical power to steady the two wavelengths.