Laser ablation in liquid is becoming an important technique for the generation of nanoparticles (NPs). Until now only pulsed lasers have been used; this is a pioneer work, using high-power, high-brightness continuous-wave (CW) fibre laser ablation in liquid, for the generation of NPs. A mechanism is proposed based on experimental observations, including high-speed imaging and emission spectroscopic analysis of the ablated plume. Three different target materials (Titanium, Nickel and Alpha-aluminium-oxide), submerged in either water or sodium dodecyl sulphate (SDS) solution at various concentrations were used. The characterisation of the generated metal-oxide NPs, in terms of size, size-distribution, shape, chemical composition and phase structure was carried out by UV-Vis photo-spectroscopy, transmission electron microscopy (TEM), high-resolution TEM with energy-dispersive X-rays spectroscopy and X-ray diffraction. This study paves a route towards a new application of CW fibre lasers. The book is useful to engineering students, professional engineers, researchers, academicians and scientists in materials, NPs characterisation, mechanical, laser processing and related disciplines.