Advanced Fiber Laser Technology And Its Applications In Optical Sensing & Optical Microwave Generation

Fiber laser technology is one of the most important technologies in optics (photonics), due to its important applications in optical fiber sensing, optical fiber communications, manufacture industry and so on. This thesis focuses on research of advanced fiber laser technologies, which include multi-wavelength fiber laser technology, Fourier domain mode locking (FDML) fiber laser technology and dual-wavelength single frequency (single longitudinal-mode) fiber lase technology, and their applications in optical sensing and photonic generation of microwave signals.To begin with, the history of fiber lasers and the research progress of several important fiber laser technologies are introduced, and the development trend of fiber laser research is summarized.Then, multi-wavelength Erbium-doped fiber laser technology based on hybrid gain or four-wave-mixing (FWM) effect is investigated. Wavelength-spacing tunable multi-wavelength Erbium-doped fiber laser incorporating a semiconductor optical amplifier is achieved, and wavelength-spacing tunable multi-wavelength Raman and Erbium-doped fiber laser is proposed. Multi-wavelength Erbium-doped fiber technology based on dispersion-shifted fiber (DSF) or photonic crystal fiber (PCF) FWM effect is investigated. It is the first time, as far as we know, stable multi-wavelength lasing is achieved for the multi-wavelength Erbium-doped fiber by employing a PCF which is used as both the FWM media and the filter component. PCF, which plays an important role in the development of the advanced fiber laser technologies, is introduced and several designs of the highly bireferingent PCF are proposed. Examples for PCF's applications in a multi-wavelength Raman fiber laser, a wavelength switchable fiber laser and an active mode-locking fiber laser are demonstrated.Furthermore, FDML fiber laser's application in optical sensing is developed. The concept and the operation principle of the FDML fiber laser are firstly introduced. Then we build up a continuous-wave FDML fiber laser and demonstrate its application for fiber Bragg grating (FBG) interrogation. For the first time, a spectrum-limited FDML fiber laser, which is a big step for the progress of FDML fiber laser technology, is proposed, and is utilized in FBG multi-point sensing system. Long distance strain sensing based on the spectrum-limited FDML fiber laser incorporating a Raman amplifier is demonstrated for the first time. Finally, dual-wavelength single frequency fiber laser technology and its application in optical microwave generation are investigated. A fiber Bragg grating pair (FBGP) with the function of narrow-band filtering is achieved by using our FBG fabrication system and is used to achieve single-wavelength and dual-wavelength single frequency fiber lasers. The FBGP based dual-wavelength single frequency fiber laser is used for optical microwave generation. A highly sensitive temperature/strain sensing system based on the FBGP and a single frequency laser is also demonstrated. Two polarization-sensitive FBGs are written in a birefringent fiber with high Erbium concentration to achieve a dual-wavelength single frequency fiber laser and their polarization-dependent transmission specta are measured. Microwave signal with a frequency up to 46 GHz is achieved base on the dual-wavelength single frequency fiber laser. Finally, one other method for photonic generation of microwave signals and a novel microwave photonic filter based on an active mode-locked fiber laser structure are introduced.This experimental research-based thesis, supplemented by theoretical research, aims to achieve technical programs for specific fiber lasers and their applications. The thesis will be of great significance for the development of the advanced fiber laser technology and the promotion of applications of the advanced fiber laser technology.