Appl. Phys. Lett. 101, 071110 (2012)

Credit: © AIP 2012

Laser ablation techniques for fabricating micro- and nanoscale structures on and within a sample are well established. However, machining curved surfaces and trenches can be a challenging task because it requires precise beam steering, sample rotation and translation simultaneously. Now A. Mathis and co-workers from Université de Franche-Comté in France have developed a convenient scheme for making curved profiles in both transparent and opaque materials. Essentially, they exploit the non-diffracting and accelerating characteristics of an Airy beam — a special type of laser beam that possesses a strongly localized intensity lobe and has a propagation trajectory with a curvature transverse to the direction of propagation. They generated the accelerating beams by using a spatial light modulator to apply appropriate spatial phase to 100-fs-duration Gaussian laser pulses from a 5-kHz Ti:sapphire laser operating at a wavelength of 800 nm. The beams were used to make surfaces with curvatures of 70 μm in 50-μm-thick diamond and 120 μm in 100-μm-thick silicon. Curved trenches in silicon were also fabricated. Because different pulse durations can be used to create different structures with different curvatures, the team anticipates a diverse range of applications for the approach. RW