An analytical model is presented describing the temporal intensity contrast determined by amplified spontaneous emission in high‐intensity laser systems which are based on the principle of chirped pulse amplification. The model describes both the generation and the amplification of the amplified spontaneous emission for each type of laser amplifier. This model is applied to different solid state laser materials which can support the amplification of pulse durations . The results are compared to intensity and fluence thresholds, e.g. determined by damage thresholds of a certain target material to be used in high‐intensity applications. This allows determining if additional means for contrast improvement, e.g. plasma mirrors, are required for a certain type of laser system and application. Using this model, the requirements for an optimized high‐contrast front‐end design are derived regarding the necessary contrast improvement and the amplified “clean” output energy for a desired focussed peak intensity. Finally, the model is compared to measurements at three different high‐intensity laser systems based on Ti:Sapphire and Yb:glass. These measurements show an excellent agreement with the model.

中文翻译：

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大功率CPA激光系统中放大的自发发射的产生。

提出了一个分析模型，该模型描述了基于chi脉冲放大原理的高强度激光系统中放大的自发发射所确定的时间强度对比度。该模型描述了每种类型的激光放大器的放大自发发射的产生和放大。该模型适用于可以支持脉冲持续时间放大的不同固态激光材料。将结果与强度和注量阈值进行比较，例如，由在高强度应用中使用的某些目标材料的损伤阈值确定。这允许确定某种类型的激光系统和应用是否需要用于对比度改善的附加装置，例如等离子镜。使用此模型，可以得出关于优化的高对比度前端设计的要求，其中涉及必要的对比度改进以及针对所需聚焦峰值强度的放大“干净”输出能量。最后，将模型与基于Ti：Sapphire和Yb：glass的三种不同高强度激光系统的测量结果进行比较。这些测量结果显示出与模型的极佳一致性。