Semiconductor disk lasers for high brightness with broad tuning

Semiconductor disk lasers (SDLs), also known as vertical external-cavity surface-emitting lasers (VECSELs) are optically-pumped semiconductor lasers, with oscillation perpendicular to the epitaxial gain structure. Importantly they have an external laser resonator, typically millimetres up to tens of centimetres in length, and therefore differ significantly from the more common VCSEL format in terms of laser operating characteristics. SDLs are in many ways more akin to conventional doped dielectric solid-state lasers; however, they have outstanding wavelength flexibility combined with their excellent beam quality, where their wavelength versatility stems from semiconductor bandgap and quantum well engineering in the gain structure and the fact that their fundamental spectral coverage can be further extended by efficient, intra-cavity nonlinear frequency conversion. This talk will give an overview of SDLs with particular emphasis on the spectral coverage achieved – design, principles of operation, materials, and typical performance – and will review the various techniques used and results obtained for continuous wave operation, intra-cavity frequency filtering, and nonlinear frequency conversion, including recent work at the IoP on intra-cavity-pumped diamond Raman lasers.