Sorokin Evgeni, Kalashnikov Vladimir L, Mandon Julien, Guelachvili Guy, Picqué Nathalie, Sorokina Irina T
Institut für Photonik, TU Wien, Gusshausstr. 27/387, A-1040 Vienna, Austria.
New J Phys. 2008 Aug;10. doi: 10.1088/1367-2630/10/8/083022.
We demonstrate chirped-pulse operation of a Cr : YAG passively mode-locked laser. Different operation regimes of the laser are extensively investigated in the vicinity of zero dispersion both experimentally and numerically. It is shown that for a given laser configuration, transition to the positive dispersion regime allows a 5-fold increase in the output pulse energy, which is otherwise limited by the onset of the multipulsing or 'chaotic' mode-locking. The output pulses have 1.4 ps duration and are compressible down to 120 fs in a 3 m piece of silica fiber, enabling supercontinuum generation in a nonlinear fiber. The spectrum shape and operation stability of the chirped-pulse regime depend strongly on the amount and shape of the intracavity dispersion. The numerical model predicts the existence of the minimum amount of the positive dispersion, above which the chirped-pulse regime can be realized. Once located, the chirped-pulse regime can be reliably reproduced and is sufficiently stable for applications.
我们展示了Cr:YAG被动锁模激光器的啁啾脉冲运转。在零色散附近，通过实验和数值模拟广泛研究了该激光器的不同运转状态。结果表明，对于给定的激光器配置，向正色散状态的转变可使输出脉冲能量增加5倍，否则该能量会受到多脉冲或“混沌”锁模起始的限制。输出脉冲持续时间为1.4 ps，在一段3 m长的石英光纤中可压缩至120 fs，从而能够在非线性光纤中产生超连续谱。啁啾脉冲状态的光谱形状和运转稳定性强烈依赖于腔内色散的量和形状。数值模型预测存在正色散的最小量，超过该量即可实现啁啾脉冲状态。一旦找到该状态，啁啾脉冲状态就能可靠地再现，并且对于应用来说足够稳定。
