Research Of The Narrow Line-Width Erbium-Doped Fiber Laser And Its Sensing Properties

The single-frequency fiber laser with very narrow line-width is one important developing direction of lasers. Extremely narrow laser spectra line-width make laser have very good coherent property. In recent years, with its unique advantages such as single-frequency, extremely narrow line-width, long coherence length and easy to form all fiber structure and so on, single-mode narrow line-width fiber laser can be widely applied as a highly coherent degree light source in the national defense and civil domains such as optical fiber communication, optical sensing and high precision, long distance coherent detection system and so on.At present, the research of the narrow line-width fiber laser mainly focuses on the optimization design of cavity structure, line-width compression method, laser mode and output characteristics, and so on. Some sensing characteristics research of line-width fiber laser are mainly concentrated on the method of obtaining sensing information by using active cavity structure by establishing the relationship between the cavity structure parameters and the laser output spectrum, the method of realizing sensing by using optical time domain reflecting technology and the method by using beat signal, etc.In this paper, the narrow line-width erbium-doped fiber laser and its sensing. characteristics are theoretical and simulation studied. A new type of narrow line-width erbium-doped fiber laser structure is proposed and the basic sensing properties of the multi-longitudinal mode DBR fiber laser are studied. Main contents are as follow:1. The output characteristics of the line cavity DBR fiber laser are simulated. The relationship between cavity length and cavity mirrors reflectivity and longitudinal mode width and longitudinal mode interval are got.2. Expressions of output power, threshold power and the slope efficiency of the erbium-doped fiber laser are deduced. The output characteristics of the circular cavity erbium-doped fiber laser are simulated. A conclusion of an optimal matching relationship among the erbium-doped fiber length, doping concentration and pump power are demonstrated.3. A new kind of narrow line-width erbium-doped fiber laser structure with Fabry-Perot etalon as the frequency selective method and saturated absorber stabilizing frequency method is proposed.4. A kind of temperature and pressure active sensing system based on multiply-longitudinal-mode DBR fiber laser beat frequency effect is proposed. After this, the stress and temperature characteristics are theoretical and simulation researched.