High Average Power Mid Infra Red Generation

在中红外区域中，从大约3微米到10微米，除了一些显著的情况之外，例如二氧化碳激光器，平均功率在10 W及以上范围内的高平均功率连续波、波长灵活的基于激光的源是不常见的，并且在技术上具有挑战性。在大气传输窗口中，这些潜在源的应用包括聚合物加工、遥感和军事对抗。该研究方案的目标是应用差频混频技术，部署高平均功率光纤激光器，以实现这一重要光谱区域的功率缩放，重点最初放在3-4微米区域的大气传输窗口上。在第一种情况下，将使用工业规模的Yb和Er基光纤激光器，其平均功率分别在300 W和100 W的范围内，其差频将允许在3.5微米范围附近的相对宽的可调谐操作。在周期性极化的锂离子电池中将发生差频混频。为了扩展可调谐性，将使用使用受激拉曼的高效光谱移位，然而，对于超过3-4微米大气传输窗口的操作，将研究替代非线性晶体的使用。

In the mid infra-red region, from about 3 to 10 microns, with the exception of some notable cases, such as the carbon dioxide laser, high average power continuous wave, wavelength flexible laser based sources with average powers in the range of 10W and above are uncommon and technically challenging . In the atmospheric transmission windows, application of such potential sources includes machining of polymers, remote sensing and military countermeasures. The objective of this research programme is the application of difference frequency mixing techniques deploying high average power fibre lasers to enable power scaling in this important spectral region, with emphasis initially placed on the atmospheric transmission window in the region of 3-4 microns. In the first instance, use will be made of industrial scale Yb and Er based fibre lasers, with average powers in the region of 300 W and 100 W , respectively, the difference frequency of which will allow relatively broad tunable operation around the 3.5 micron region. Difference frequency mixing will be undertaken in periodically poled lithium niobate. To extend the tunability, highly efficient spectral shifting using stimulated Raman will be used, however for operation beyond the 3-4 micron atmospheric transmission window the use of alternative non linear crystal will be investigated.