Precise simulation of solid-state amplifiers

脉冲和超短脉冲激光器在各种技术应用中得到了广泛的应用，尤其需要研究强大的超短脉冲激光器，因为这类激光器对汽车工业的未来发展具有重要意义。由于激光谐振器的发展有限，为了获得更高效、更强大的激光光源，必须将研究重点放在新型激光放大器上，仿真是激光光源进一步发展的重要工具。原因是激光放大器中复杂的物理现象。通过模拟，工程师可以分析这些现象并优化激光放大系统。这种模拟必须包括用速率方程描述的双折射、退偏、热效应和非线性效应的精确三维模拟。尽管人们在开发新的激光光源方面做了大量的研究，但对新的激光模拟工具的开发却被忽视了。因此，本研究项目的目的是为激光放大器的仿真开发新的模型和算法。在这里，我们关注的是像Yb：YAG这样的固体晶体作为激活介质。此外，我们还考虑了具有高或低重复频率的短脉冲和超短脉冲激光的放大器。仿真模型考虑了激光放大器的热效应、去偏振效应和光谱行为。对单程、双程和多程激光放大器进行了模拟。主要的研究问题是必须结合哪种仿真技术才能获得最准确的仿真结果。为此，必须找到新的模拟技术。其目的一方面是为了获得准确的仿真结果，另一方面是为了找到计算量小的算法。这就需要对不同的仿真算法进行比较。

Pulsed and ultrashort pulsed lasers are used in various technical applications.In particular research on powerful ultrashort pulsed lasers is needed, since such lasers are important for future developments in automotive industry. Since the development of laser resonators is limited, research has to focus on new laser amplifiers in order to archive more efficient and powerful laser sources.Simulation is an important tool for further development on laser sources. Reasons are the complex physical phenomena in laser amplifiers. Using simulation, engineers can analyze these phenomena and optimize laser amplification systems. Such simulations have to include accurate 3-dimensional simulation of birefringence, depolarization effects, thermal effects, and nonlinear effects described by rate equations.Although lots of research has been done on the development of new laser sources, the development of new simulation tools for lasers was neglected. Thus, the aim of this research project is to develop new models and algorithms for the simulation of laser amplifiers. Here, we focus on solid-state crystals like Yb:YAG as active medium. Furthermore, we consider amplifiers of short and ultrashort pulsed laser beams with high or low repetition rate. The simulation models take into account thermal effects, depolarization effects, and spectral behavior of the laser amplifier. Single pass, double pass, and multi pass laser amplifiers are simulated. The main research question is which kind of simulation techniques have to be combined to obtain most accurate simulation results. To this end, new simulation techniques have to be found. The aim is, on the one hand, to obtain accurate simulation results and, on the other, to find algorithms with low computing effort. This requires the comparison of different simulation algorithms.