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

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).