Development Of 980nm Fiber Grating External Cavity Semiconductor Lasers

Dense wavelength division multiplexing (DWDM) is an important technology of fiber communication system. The laser source, as the important portion of DWDM optical fiber communication system, must satisfy some strict requirements such as stable lasing wavelength, and narrow line-width, etc. Fiber grating external cavity semiconductor laser (FGESL) has received considerable attention as a promising source to satisfy these strict requirements; 980nm semiconductor laser is widely used in the design of erbium doped fiber amplifier(EDFA). The coupling efficiency of 980 semiconductor laser and single mode fiber (SMF) has become the most fundamental problem for engineers and researchers to solve. Coupling efficiency affects the performance of EDFA and decides fiber communication relay distance. Thus people pay more and more attention on researching it.In this paper, we used wedge-shaped cylindrical lensed fiber bragg grating (FBG) to form an fiber grating external cavity semiconductor laser, finally we obtained stable lasing wavelength output. The theoretical and experimental researches completed in the thesis are as follows:(1) Made a detailed analysis to the work principle of FGB external cavity semiconductor laser, included luminescent mechanism, mode selection theory, equivalent cavity theory, speed equation, fiber coupling theory and so on.(2) Based on the equivalent cavity theory, we took semiconductor laser's end surface reflectivity, external cavity length and fiber grating together into account, simulating and calculating basic parameters of fiber grating external cavity semiconductor laser by Matlab software, such as: threshold gain, output power, line width and side-mode suppression ratio, then we obtain the optimized parameters.(3) Analyzed the characteristics of fiber Bragg grating, and used the optimized reflectivity of fiber grating, we determined other parameters of fiber grating , including its cycle, length.(4) Aimed at 980nm semiconductor laser coupling with wedge-shaped cylindrical lensed fiber, through the coupling equation, we simulated and attained optimized parameters of micro lensed fiber (half wede angle and curvature radius) and the best distance between them by Matlab software. (5) Introduced the butterfly-shaped packaging for 980nm fiber grating external cavity semiconductor laser.(6) Through testing the output characteristics of 980nm fiber grating external cavity semiconductor laser to confirm the optimization model was accurate.