Second Harmonic Spectroscopy with Infrared Free Electron Lasers
Second harmonic generation is a nonlinear optical effect that occurs at surfaces and non-inversion symmetric media.
This project will investigate the efficiency of second harmonic generation in the mid-infrared spectral region from
semiconductors and metal surfaces, as well as micro-structured hybrid metal-semiconductor interfaces. Making use of
the picosecond pulses and spectral tunability of the mid-infrared free electron laser at the FHI, these investigations
can be performed as a spectroscopy, specifically addressing spectral resonances in the nonlinear optical response of
The applicant should provide a good background in optics and solid state physics, as well as a strong
affinity to experimental work
Frequency Upconversion of Infrared Free Electron Laser Radiation
Time-resolved pump-probe experiments with the mid-infrared free electron laser (IR-FEL) at the FHI as pump pulse and
femtosecond NIR pulses from a table top laser as probe pulses require precise knowledge and control of the relative
timing of these laser pulses. For that purpose, frequency upconversion of the IR FEL pulses with near-IR table top
laser pulses in a nonlinear optical crystal will be implemented. The project will start out with proof-of-principle
experiments using a multi-nanosecond YLF near-IR laser. In a second stage, the experiment will be performed with a
synchronized femtosecond pulse train from a fiber laser. Ultimately, this setup will implemented to be used as relative
timing feedback between the FEL and near-IR laser in time-resolved pump-probe experiments.
The applicant should provide a good background in optics, preferably nonlinear or ultrafast optics,
as well as a strong affinity to experimental work.