Investigation of techniques for nonlinear frequency conversion of high power fibre lasers to the visible wavelength band

该项目将研究一种新的方法，用于在可见波长范围内从光纤激光器产生非常高的连续波输出功率，其目标是在功率、效率和波长灵活性方面展示远远超出当前最先进技术能力的性能水平。这项工作的动机主要是基于激光制造，特别是增材制造（3D打印）对可见波段高功率激光源的需求不断增长，因为重要金属（如铜）的吸收率显著提高。该方法基于使用一种新颖的内部非线性频率转换方案，该方案可用于具有显著（即不可忽略）腔损失的激光器（如包层泵浦光纤激光器），而不会对性能产生不利影响。其目的是证明该方案与绿色的千瓦级发电兼容，并提供灵活性，以满足可见光波段其他波长的高功率水平的需求。改进的性能将直接有利于基于激光的制造中的应用，其中增强可见光吸收至关重要，以及许多其他应用（例如生物医学成像，DNA测序，光泵浦，显示技术）。

This project will investigate a new approach for generating very high continuous-wave output power from fibre lasers in the visible wavelength regime with the ambition of demonstrating levels of performance in terms of power, efficiency and wavelength flexibility that go well beyond the capabilities of the current state-of-the-art. The work is motivated mainly by the growing demands of laser-based manufacturing, and particularly additive manufacturing (3D printing), for high power laser sources in the visible band due to significantly greater absorption in important metals, such as copper. The approach is based on the use of a novel scheme for internal nonlinear frequency conversion that can be used with lasers (such as cladding-pumped fibre lasers) that have significant (i.e. non-negligible) cavity losses without detrimentally affecting the performance. The aim is to show that this scheme is compatible with kilowatt-class power generation in the green and that it offers the flexibility to address the needs for high power levels at other wavelengths in the visible band. The improved performance will directly benefit applications in laser-based manufacturing where enhanced absorption at visible wavelengths is crucial, as well as many other applications (e.g. bio-medical imaging, DNA sequencing, optical pumping, display technologies).