Study On LD Pumped Yb³⁺-doped Ultrafast Laser Systems

The all-solid-state mode-locked lasers and the amplifiers of ultrafast lasers are two hot topics of research recently. As a combine of those research fields, this paper had performed theoretic and experimental studies of the Yb³⁺-doped all-solid-state mode-locked lasers and the Yb³⁺-doped photonic crystal fiber amplifiers of ultrafast lasers. The research works in detail are the following:1. The CW mode-locked experiment of a novel crystal Yb:GSO was obtained. The width of mode-locked spectrum is 1.5nm and the center wave is at 1033nm. The max output power is 156 mW.2. The parameters that influence the efficiency of self-frequency-doubled (SFD) were analyzed and the optimization condition was found out. According to the theory, a LD end-pumped high efficient SFD Yb:GdYAB laser was built. A maximum efficiency from LD to green laser of 17.2% was obtained. A mode locked laser using SESAM was built and stable cw mode locked laser pulses were obtained, which provided a good ultrafast pulse source for amplifiers.3. Regarding the Yb³⁺ a quasi-four level media if the laser wavelength is above 1 micrometer, the law of the signal, pumped and ASE power in a Yb³⁺-doped fiber were obtained by the rate equations. Also the propagation of ultrafast pulses in a fiber was emulated numerical, which showed that nonlinear is the main effect in a fiber while amplifying.4. Using a Yb³⁺-doped photonic crystal fiber with high NA of cladding fiber as gain media, a ultrafast pulse amplifier was built. While the input signal pulse had a width of 2.3ps and average power of 100mW, a max output power of 2.4W with width of 3.0ps was obtained.5. In order to measure the width of ultrafast pulse, an autocorrelator driven by a stepper motor was built to measure the width of ultrafast pulses. It works well and has been used in experiments.