Wavelength Tunable Fiber Lasers Based On Sampled Bragg Gratings

With the development of high-capacity optical fiber communication system, the WDM (Wavelength Division Multiplexing) technology becomes a hot subject and a research frontier. As one of the key component of WDM system, wavelength tunable fiber laser attracts researchers' attention because it is naturally compatible with the fiber and can be accurately tuned in ITU-T wavelength range.In this thesis, a novel kind of wavelength tunable fiber laser based on linear cavity erbium-doped fiber laser (EDFL) and sampled fiber gratings was designed. The achievements included in this thesis are as follows:1. The operating principle of erbium-doped fiber laser was analyzed. The properties of erbium-doped fiber were demonstrated. By using Giles's model and the theory of rate equation, erbium-doped fiber amplifier (EDFA) was simulated.2. Based on the theoretical analysis, numerical analysis of fiber Bragg gratings was made and the rules how grating's parameters influence the reflective spectra and time delays were given. The fabrication method of fiber grating was studied, and fiber grating was made experimentally.4. By using transfer matrix method, numerical analysis for the reflective spectra and time delay of sampled fiber gratings were made. The influence of sampled fiber grating's parameters on the reflective spectra was analyzed. An apodization method was used to optimize the sampled fiber gratings, the effect of which was further proved by numerical simulation.5. A novel kind of wavelength tunable fiber laser based on linear cavity erbium-doped fiber laser (EDFL) and sampled fiber gratings were designed. First the model of EDFL with Bragg gratings as reflectors was established and simulated, the influence of EDFL's parameters on the laser power spectra and slope efficiency was analyzed. The designed tuning mechanism was then applied to the model and was simulated. Finally the experiments of this wavelength tunable fiber laser were made and the experiment results were given. The experiment results show that this kind of wavelength tunable fiber laser can obtain a large wavelength tuning range by tuning sampled Bragg gratings slightly. The laser can be tuned quasi-continuously to correspond with wavelengths of ITU-T grid.