Record low pulse-energy micromachining in bulk glass with an ultrafast laser

In this paper, we report the machining of various types of glasses by femtosecond pulses generated directly from a Ti:sapphire oscillator with less than half of that pulse energy. In our experiments we used a Ti:Sapphire laser pumped by a double-frequency Nd:YVO/sub 4/ laser. Our strategy is to tightly focus sub-30fs pulses with a high numerical aperture objective lens while optimizing the bandwidth and pulse temporal and spatial shape to achieve minimum threshold energy for permanent structural damage.