掺铥光纤激光器的波长调谐特性研究

Numerical Study on Wavelength Tuning Characteristics of Thulium-Doped Fiber Lasers

摘要:

本文基于简化的二能级激光系统和均匀展宽理论模型,利用原子速率方程和功率传输方程建立了掺铥光纤激光器的理论模型,并以环形腔掺铥光纤激光器为例,通过Matlab编程数值模拟研究了其出射功率和波长调谐范围与腔内损耗、掺铥光纤长度、输出耦合比、泵浦波长和泵浦功率等激光器参量的关系。数值模拟结果说明,降低激光器腔内损耗、提高泵浦激光功率和优化掺铥光纤长度可以提高掺铥光纤激光器的出射功率和增加波长调谐范围,而增加输出耦合比虽能提高激光功率,却减小了波长调谐范围。经过参数优化,在腔内总损耗为3 dB、输出耦合比为10%情况下,通过提高泵浦激光功率和优化掺铥光纤长度,掺铥光纤激光器的波长调谐范围可达528 nm (1660~2188 nm),高于目前已报道的实验结果。部分模拟结果与文献报道的实验结果进行了对比,较好的证实了模型的准确性。研究工作对于掺铥光纤激光器的设计和发展具有重要的理论参考价值和指导意义。

Abstract:

Output power characteristics of thulium-doped fiber ring lasers are studied numerically through Matlab programming with a theoretical model developed based on the fundamental atomic rate equations and power propagation equations of the simplified two-level laser system and the homogeneous broadening theoretical model. The effects of total intra-cavity loss, active fiber length, output coupling ratio, pump wavelength and pump power on output power and laser emission wavelength tuning range are studied. The numerical simulation results show that minimization of intra-cavity loss and increase of the pump power as well as optimization of active fiber length is very important for the thulium-doped fiber laser to improve the output power and increase the wavelength tuning range. In the meantime, increase of the output coupling ratio can also improve the laser output power, but reduce the wavelength tuning range. A broad wavelength tuning range up to 528 nm (1660~2188 nm) is achievable by increasing the pump power and optimizing the length of thulium-doped fiber when the total intra-cavity loss and output coupling ratio are 3 dB and 10%, respectively. It is much higher than the experimental and simulated results reported so far. Partial simulation results are compared with those experimental results in the literature, and the accuracy of the model is well confirmed. These findings have important theoretical reference value and guiding significance for the design and development of thulium-doped fiber lasers.