Parallel Diffractive Multi-beam Ultrafast Laser Microprocessing

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 laser systems can provide milli-joule level output. Therefore, significant energy attenuation causes a great deal of energy loss. With this limitation in mind, a multi-beam ultrafast laser processing, where the milli-joule output is split into many desired diffracted beams, is proposed in this book. The multi-beam patterns are generated by phase modulation through a Spatial Light Modulator (SLM) and can be applied in real time with synchronized scanning methods. The results demonstrate high precision parallel ultrafast laser micro/nano fabrication with greatly increased efficiency and throughput.