Laser providing stable femtosecond pulses

摘要

A femtosecond dye laser comprises a dye amplifier assembly (30) pumped by a mode-locked neodymium YAG laser (35) operating with frequency doubling. The main dye laser cavity as defined on one side of the amplifier assembly (30) by a linear prism structure (11 and 14) leading to an outlet mirror (15), and on the other side of the amplifier assembly by an assembly (20) constituting an anti-resonant mirror disposed about a saturable absorption device (40). An error signal is tapped by leakage from one of the mirrors (22) and is spectrally analyzed and compared with a reference wavelength (at 50) enabling a high tension amplifier (60) to be controlled to act on a piezo-electric stack (19) in order to fix the position of the outlet mirror (15) so as to adjust the optical length of the cavity as a function of the spectral characteristics of the pulses it produces.