| Information explosion stimulates the dramatic increase of global telecommunication service and brings forward higher requirements for the capability of telecommunication network on transfer information. DWDM and OTDM are effective approaches to realize the expansion of optical telecommunication system, and the generations of multi-wavelength signal and highly repeated frequency super-short-pulse are the two corresponding key technologies. According to the requirements from military, industry machining and space telecommunication, it becomes more urgent to improve the output power of optical fiber laser. This dissertation concentrates on in-depth research on the coherent combination technology of the double-cladding fiber lasers and the Erbium-doped single-mode fiber lasers both in theory and experiment. Besides these, multi-wavelengh fiber lasers and its wavelength-narrowed mechanism are also investigated. Some meaningful results are achieved, which include:1. The function of 3dB fiber loop mirror (FLM) in fine wavelength partition is studied. With this theory, a novel narrow linear band, dual-wavelength switchable Er-doped fiber laser is realized.2. An unpumped Er-doped fiber and broadband fiber Bragg grating (FBG) with high reflectivity is served as an auto-tracking filter, where the space hole-burning effect appears when the laser signal travels and forms standing wave, thus the generation of multi-longitudinal-mode is suppressed. Then the high birefringence fiber loop mirror (HiBi-FLM) is introduced to act as comb-liked wavelength filter. Because of the convolving effect between auto-tracking filter and the comb filter, the narrow linear band, multi wavelength optical fiber laser is acquired.3,A design of introducing a polarizer into the Michelson cavity is presented, which lead to further improvement of the coherent combinative effect. Moreover, the necessity to introduce such a polarizer is analyzed qualitatively in theory. Under the condition of using only one FBG to act as a common cavity reflection mirror and wavelength filter in the improved structure, we get the result that the higher the reflectivity of FBG is, the higher the output power of compound cavity is obtained under the same pumped power, which provides valuable experiences for the coherent coupling of the high power fiber lasers.4,On base of part 3, active mode-locked Er-doped fiber laser is realized by using only a FBG to serve as the common mirror and wavelength filter, and the high-repeated-frequency, bright and dark pulse laser is acquired. Without introducing any other additional equilibrium devices, the high repeated frequency, equal amplitude 2-order rational harmonic mode locking acquired is observed.5,Some research on large-mode-area double-cladding Yb-doped fiber laser are carried on, which are listed as follows: Firstly, writing low reflectivity FBG directly on the large-mode-area double-cladding Yb-doped fiber as the output cavity mirror, we realized a narrow linearband, multi-wavelength double-cladding fiber laser. Secondly, based on the requirement of coherent combination, by using of the self-made 1060nm small signal resource (16mW) and the large-mode-area double-cladding Yb-doped fiber as gain media, master oscillating power amplification (MOPA) is achieved successfully. Thirdly, investigation on passive Q-switched Yb-doped fiber laser with a saturation-absorber is carried on. Finally, an all homemade sample laser with the Yb-doped double-cladding fiber is realized cooperatively, in which all of the components are made in China.
|
PDF Full Text Request