| Summary: | 碩士 === 國立交通大學 === 光電(科學)研究所 === 83 === In this thesis, we have established a numerical model of kerr
lens mode-locking(KLM) Ti:sapphire laser cavity by ABCD matrix.
In this model, we can simultaneously consider the spatial and
temporal effects including self-focusing, gain guiding, free
space propagation, group velocity dispersion (GVD), bandwidth
limiting, near resonance phase shift, nonlinear absorption and
self-phase modulation (SPM). At first, We obtained a solution
of a stable cavity, then modified the term of gain saturation
to simulate the pulse grown of this laser by assumming CW mode
and KLM mode coexisting. We found that there is a turing
point in the time evolution of output pulsewidth, where GVD
optimally compensates SPM to achieve the limitation of pulse
compression. In consequence of self-focusing, the gain of KLM
mode becomes larger than that of CW mode, and the pulse is
further compressed by the rise of pulse energy. Finally, the
KLM mode drains out all of the energy stored in the gain medium
and quenchs CW mode, a steady-state solution of mode-locked
pulse train is obtained.
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