Development On Single-Frequency Narrow Linewidth Fiber Laser Based On Quasi-π Phase Shifted Fiber Bragg Grating

Compared with other traditional lasers, fiber lasers have the advantages of compact structure, high coupling efficiency, pumping threshold low, wide tuning range, good heat dissipation effect, light weight, and so on. Nowadays they have been widely used in modern optical communication system, military, precision machining, medical equipment and other fields. At present, the research on fiber lasers mainly focuses on compressing linewidth, increasing the output power and the realization of tunable multi-wavelength output. The narrow linewidth fiber laser is an important direction of the development of fiber lasers. In addition to the advantages of the fiber laser, narrow linewidth fiber laser with narrow linewidth, long coherence length, low noise, easy realization of high power. The narrow linewidth fiber laser is widely used in remote sensing, remote fiber communication, high precision spectra and optical fiber sensing system, which has a broad market prospect.The research target of this thesis is about designing the 1550 nm narrow linewidth fiber laser, which is based on quasi-π phase shift fiber Bragg grating Research contents including the design of a narrow linewidth laser structure, design and fabrication of a quasi-π phase shift fiber Bragg grating, design and fabrication of a linewidth fiber laser based on the quasi-π phase shift fiber Bragg grating and a 980nm LD. The quasi-π phase shift fiber Bragg grating theoretical derivation and fiber laser structure design is the key point in the research, the main research work is divided into three parts as follows:1. The basic principle and characteristics of the fiber laser are briefly described. The basic working principle of the Er3+ doped fiber laser is analyzed. Several methods and their advantages and disadvantages of the single frequency narrow linewidth fiber laser are introduced.This thesis presents how to fabricate quasi-π phase shifted fiber grating and build a narrow linewidth fiber laser. Study the relationship between the reflection properties of the quasi-π phase shift fiber Bragg grating and other parameters. The thesis analyzes the influence of phase shift fiber Bragg grating wavelength factors, and also produces a quasi-π phase shift fiber Bragg grating,which is used to build the narrow linewidth fiber laser.2. A home-made 980nm pump laser is used to build a narrow linewidth fiber laser based on quasi-π phase shifted fiber grating. Three different pumping schemes are discussed, and the linewidth of fiber laser is measured.