Study On Ultra-short Pulse Yb-doped Fiber Laser And Amplifier

Rare-earth doped silica fibers have been used for many years to create continuous-wave lasers. And Er-doped fiber amplifiers are now widely used in telecommunications. In addition, cladding pumped fiber allows the efficient conversion of multimode radiation from high power, low cost, broad-stripe semiconductor laser into the single-mode emission of fiber laser. Ultra-short pulse laser system based on fiber lasers and amplifiers are the best choice for ultra-short technology applications because they are miniaturization, freedom from cooling, compact and low cost. With its broad gain bandwidth and high optical conversion efficiency, Yb-doped silica fiber represents an attractive medium for the generation and amplification of high-energy ultra-short optical pulses in recent years. More and more researchers pay attention to it.The main research works and innovations of this thesis are summarized as follows:1. The fiber based chirped pulse amplifier system was studied for the first time in domestic. The figure of eight ultra-short pulse Yb³⁺ doped fiber oscillator, the high gain pre-amplifiers with different gain and structure, pulse selector, nano-second pulse pileup and double-clad fiber power amplifiers has been manufactured. The maximum pulse energy was amplified to 100 uJ with a pulse width of 381 ps. By using the traditional gratings compressor, the amplified pulse was compressed to 525 fs, and the highest pulse energy was 52 uJ. In addition, the pulse energy of 107 uJ with a pulse width of 2.7 ns was obtained. The repetition rate of these pulses was 30 kHz, and the center wavelength was 1053 nm. These are the best result in domestic. And there is no reports on the multi-function ultra-fast fiber laser system in international.2. The experiment of the single mode Yb-doped fiber amplifiers and gratings compressor was discussed. The seed pulses come from a mode-locked Yb-doped fiber ring laser. The maximum output average power of the fiber laser is 7mW at 25.4MHz repetition rate with a pulse width of 56ps. The maximum power of the pulses was amplified to 140mW corresponding to a gain about 13dB by using a single mode Yb-doped fiber. The amplified pulses were compressed by using the traditional gratings compressor. The minimum width of the pulses is compressed to 440 fs. The average power of the pulses after the compressor is 43mW corresponding to a peak-power of 3.8kW.3. Steady state numerical analysis is performed for the Yb-doped double clad fiber laser after the theoretical model is built. Yb-doped double clad fiber laser was developed with maximum output power of 7.2 W at 1070 run. The slope efficient is up to 76%, and the total optic-optic conversion efficiency is 47%.