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Shaping Laser Pulses

How design and create the optimal laser pulse for a given reaction?

The femtosecond lasers used in our experiments are inherently spectrally very broad. From Heisenbergs uncertainty relation one knows that a very short pulse must be undetermined in energy (energy µ 1 / wavelength). A femtosecond pulse is typically 10 nm wide (spectral bandwidth) and this opens up a new and exciting way of controlling the molecules that we excite. Almost arbitrary pulse shapes can be obtained by ”shaping” the femtosecond laser pulses.

We use an optical grating in conjunction with an 2D-shaper, where we can change the amplitude and phase of the individual spectral components inside the bandwidth of the pulse. This allows use to design optimal pulses that are optimized for specific excitations and molecules!

The project involves understanding the shaper, the light-molecule interactions, and designing optimization schemes for the laser pulses. We plan to use shaped pulses for both our CARS, BPW, and Femtochemistry experiments.