Single-pulse femtosecond laser machining of glass

We describe a study of single-pulse machining of glass with 150 fs pulses at 800 nm (Ti:sapphire) and present results demonstrating in a quantitative way the dependence of the machining quality on the focal position and the pulse energy of the laser beam. We report experimental results indicating the creation of sub-diffraction limited structures. A theoretical calculation of the ablation threshold of glass is inferred from our experimental results to be 5.55 J cm^-2. Results are also presented that illustrate the dependence of the machining quality on the pulse duration used. A technique for optimizing the focal position at energies below the machining threshold is detailed and the results of a related study investigating the self-focusing of femtosecond beams in air are described. © 2005 IOP Publishing Ltd.