Fabrication Of Linearly Chirped Fiber Bragg Grating And Its Application In Fiber Laser

Linearly chirped fiber Bragg grating (LCFBG) not only has ordinary fiber Bragggrating’s advantages, such as small additional loss, anti-electromagnetic interference,stable, reliable, easy fabrication, easy connections with other fiber systems and so on,but also has the advantage of dispersion compensation. So it has been widely used in thefield of optical fiber communication and sensor. As fiber Bragg grating to be used asresonator mirrors, the structure of fiber laser become stable, reliable and compact.Without complex optical path adjustment, all-fiber laser has good quality output beam,as well as good frequency selection mechanism. These advantages make the fiber laseris of good commercial value. Ytterbium ion has a simple energy level structure, a verybroad absorption spectra and emission spectra, a long life of metastable level and highquantum efficiency, etc., making it easy to form a high density of particles inversion inthe tiny fiber core, to obtain a stable output of the laser. Therefore,Yb-dopeddouble-clad fiber laser has already become the research focus of the laser field. Thisthesis mainly includes the following contents:In the preface, the research progress of the fiber Bragg grating in opticalcommunications, fiber lasers and fiber optic sensors have been summarized respectively.From the structure and technical level, I have summarized the various methods toimprove the output power of fiber laser. Finally, several major nonlinear effects whichmay appear in the fiber have been briefly introduced.In this thesis, the coupled-mode theory of fiber Bragg grating have been introduced.By using the Runge-Kutta method and transfer matrix method, I have a numericalsimulation of linearly chirped fiber Bragg grating coupled-mode theory. Then a simpleanalysis of the theory of Yb-doped double-clad linear cavity fiber laser has been given.On the basis of it, I used numerical simulation method to find out the ytterbium-dopeddouble-clad fiber length which perfectly corresponding to the best output beam qualityand power under the experimental conditions. Later, the minimum threshold powerwhich can cause the laser to generated stimulated Brillouin scattering effect has beentheoretical estimated. Reference to the numerical simulation results and the existing laboratory conditions, we fabricated a all-fiber laser with a fiber Bragg grating as itsendoscopy, then tested its output power, tilt efficiency, threshold power and stabilitycharacteristics. To clamp the fiber steadily, we have designed and set up a fiber gratingclamp system by ourselves. By using the phase mask method, we have fabricatedLCFBG whose center wavelength is1064nm, and tested its characteristics of reflectivity,bandwidth, Bragg wavelength and the influence of environmental temperature to itthough a broadband light source which also made by ourselves.