Ultrafast lasers have been widely employed for material micro/nano processing with little thermal damage. Due to the ultra high intensity of ultrashort pulses, nonlinear absorption can be induced at the focus leading to highly localised material ablation or modification. This is now opening up applications ranging from integrated optics, through multi-photon induced refractive index engineering to precision surface micro-structuring. To ensure the non-thermal processing, input pulse energy must be kept around micro-joule level. However, running at kilohertz repetition rate, many ultrafast...