Research On Q-Switched And Mode-Locked Fiber Lasers

In recent years, fiber lasers have developed rapidly due to the demand of optical fiber communication, especially, the ultra-short pulse fiber laser which has drawn more and more attention because of its potential applications in OTDM (Optical Time Division Multiplexing) technique and optical soliton communication system. The author first summarizes the basic principle of the fiber laser and several methods to generate ultra-short pulses in the fiber laser, then discusses the Q-switched fiber laser and mode-locked fiber laser theoretically and experimentally in detail, meanwhile introduces the research on ultra-short pulses semiconductor laser with a fiber grating external cavity. The thesis focuses on ultra-short pulses fiber laser and includes descriptions on the following subjects:(1). The theoretical analysis of a Q-switched fiber laser and experimental study on the self-Q-switched phenomenon of an erbium-doped fiber laser are conducted. The self-Q-switched pulses of high erbium-doped Fabry-Perot cavity fiber laser are observed and theoretically analyzed.(2). Utilizing the non-linearity characteristics of single mode fiber- back stimulated Brillouin scattering(BSBS) and the wavelength-selecting characteristics of fiber gratings, self-Q-switched pulses are achieved from a linear cavity erbium-doped fiber laser pumping by a 980nm LD continue wave(CW) pumping, The pulse width is 2.2ns and the repetition frequency of pulses is 64.5MHz.(3). The theoretical analysis and the experimental study on an active mode-locked fiber laser are conducted. The harmonic mode-locked pulses of 2.5GHz and 5GHz are achieved and the 2-4 order rational harmonic mode-locked pulses of 2.5GHz are researched in active mode-locked erbium-doped fiber ring lasers.(4). The wavelength-tuning methods of active mode-locked erbium-doped fiber ring lasers are researched. Using fiber grating to substitute traditional wavelength-selecting components, the 8nm tuning range is realized at a repetition frequency of 2.5GHz.(5). The wavelength-tuning methods of an active mode-locked fiber laser using a LD as a modulator are researched, and two tuning methods including temperature tuning...