Jimenez Lab

Multi-kilohertz Ti:Sapphire laser amplifier system

Our group uses a novel stretcher/compressor design for our multi-kilohertz, microjoule femtosecond laser amplifier system.   The pulse stretcher before the amplifier is constructed using grisms (a grating that is bonded to a prism).   Grisms have the interesting property that they can be designed such that the ratio of third order dispersion (TOD) to second order dispersion, or group velocity dispersion, (GVD) is equal in magnitude to that of most dispersive materials. In addition, both the TOD and GVD terms are opposite in sign to material dispersion; thus, grisms are better optimized for compressing femtosecond pulses than either grating or prism pairs. The stretched pulses are amplified and then recompressed by simply passing the amplified, negatively chirped beam through a block of glass using the downchirped pulse amplification (DPA) scheme.

Amplifier Design

Grism based stretching and glass compression allows compact, easy to align, efficient dispersion management in femtosecond laser amplifier systems.  The grism stretcher/compressor setup is designed to operate over a very broad wavelength range allowing compression of tunable lasers and ultra-broadband pulses.  Using this setup we routinely generate near transform limited pulses with 40 fs pulse duration at 10-20 kHz repetition rate and 300 microjoule pulse energies.

Output spectrum and spectral phase (left) and measured compressed pulse duration (right)