Study Of Diode Pumped New Yb Ion-Doped Lasers

Yb³⁺-doped crystals have many superior properties, such as: high laser efficiency,roadband fluorescence and long radioactive lifetime, which make them suitable forunable, ultrafast and Q-swithed lasers. In this thesis, the theoretical and experimentaltudies about CW,tunable,Q-swithed and mode-locked lasers with three newb3+-doped crystals (Yb:GdCOB, Yb:LSO, Yb:GSO) were presented.The advantages and development of all-solid-state lasers with the new Yb³⁺-doped rystals are introduced. A brief introduction of the applications of the tunable andemtosecond lasers in the spectroscopy, medicine, communication, military, subtleachining was presented.The energy levels and the spectrum of the Yb³⁺-doped crystals were introduced. Theheoretical threshold of the different crystals was calculated. The rate equations of theb3+ doped crystal laser in CW operation were solved. We analyzed several factorshich influenced the laser output and obtained the optimum value by calculation. Weave the exact equations to calculate the absorption coefficient and the absorbed power ofhe thin uncoated crystal. Detailed analysis of the mode-locking theory of femtosecond ser was discussed.The CW experiments of the three new Yb³⁺-doped crystals have been demonstrated, nd the laser parameters have been optimized. TheYb:GSO laser obtained a lowhreshold of 77mW which is the lowest threshold in the world as far as we know. Theutput couplers of different transmissions have been used in the CW operation, the resultsatched the theoretic optimum transmission very well. The thermal effect was studied.e designed a simple method to measure the thermal focus length of the crystal and gavehe thermal focus length of Yb:GdCOB in the experiment.Three kinds of cavity setup were used to achieve tuned lasers. They are flat-concavedavity with one prism, three-mirror cavity with one prism, three-mirror cavity with tworisms and a slit. From the theoretical calculation and the experimental results, we makehe conclusion that the last cavity setup is most suitable for the wavelength tuning.We calculated the stable regions and the peak power on the SESAM, at the same time,ave the beam size on the SESAM and on the crystal. We achieved the Q-switchedutput with a three-mirror folded-cavity after optimizing it.