Lasers
Femtosecond Laboratory
Whenever SHG experiments require very high light intensities (as for the tiny light matter interaction lengths in thin films or for non-resonant SHG) or temporal resolution to study the dynamics of spins, lattices and electrons in a material, we use one of our two femtosecond laser systems.
Both systems consist of a regenerative amplifier in which 800 nm seed pulses from a femtosecond oscillator are amplified in an optically pumped Ti:Sapphire-crystal. Finally, 800 nm pulses with 100 fs and 2.5 mJ or 8 mJ are emitted at 1 kHz repetition rate, respectively. Each laser system operates two optical parametric amplifiers (short: OPAs) which allow for wavelength tuning. In our labs, the wavelength range between the UV (240 nm) and the mid-IR (20 μm) is accessible.
The OPA outputs typically supply either two individual SHG setups or can be combined for two-color pump-probe experiments.
Nanosecond Laboratory
In addition to the ultrafast laser labs there are two labs equipped with nanosecond pulsed lasers for spectroscopy and domain imaging projects. These are Q-switched, flash light pumped Nd:YAG lasers with pulse durations of 3 to 7 ns and pulse energies of up to 900 mJ and a repetition rate of 10 or 50 Hz. The fundamental beam of the Nd:YAG lasers (1064 nm) is frequency tripled in a THG crystal to pump an optical parametric oscillator. This results in a tunable wavelength range of 410 nm to 2500 nm.