Dispersion of femtosecond laser pulses by acoustic-optic devices

Femtosecond lasers show much promise as potential sources of choice in a number of laser micromachining applications, including semiconductors, photonics and biomedicine. Their ability for minimal damage and precise processing has been thoroughly researched for the past few years. One of the requirements for precise processing is high precision beam steering. Acousto-optic devices (AODs) are commonly used in laser direct writing systems to steer the beam with high precision and speed. However AODs cannot be applied for steering femtosecond laser beams, because, dispersion associated with acousto-optic interaction will cause serious spatial deformation on the writing spot. A detailed study of the AOD dispersion and the method to compensate this dispersion have been discussed in this paper.