Project

femtosecond laser system; nonlinear optics; quantum optics; mid-IR laser; few-cycle pulse generation; electric field synthesizer; seeding FEL; high power; high-order; harmonic generation; femtosecond laser source

Lead
Lay summary
The goal of our research is the generation of coherent soft x-rays in the so-called water window (2.3-4.2 nm). In this spectral region the absorption of water gets reduced by about an order of magnitude and enables the application of powerful imaging techniques to biological samples. The availability of the proposed laser would tremendously contribute to new insights into molecular and cell dynamics at an unprecedented spatial resolution. An extension of current state-of the art soft x-ray lasers towards the water window requires the development of novel powerful mid-infrared lasers emitting ultrashort pulses of a few tens of femtoseconds (1 fs = 1e-15 sec) which is an important work package within the frame of this project.

Direct link to Lay Summary

Last update: 21.02.2013

Number	Title	Start	Funding scheme

We propose the purchase of an optical parametric amplifier system as an add-on to our existing high-intensity laser system in order to push the physical limits of a table-top XUV source towards significantly shorter wavelengths. The requested up-grade is a commercial system (HE-TOPAS, Lightconversion Ltd.) consisting of several nonlinear amplification and frequency conversion stages which allow the production of intense mid-infrared radiation (e.g. ?=2.6 µm) when pumped with a conventional Ti:sapphire amplifier system (?=0.8 µm). The generation of powerful mid-infrared femtosecond pulses opens the door to new and exciting research areas. It allows fundamental studies of nonlinear phenomena driven by intense mid-IR laser such as nonlinear interactions in gases (e.g. filamentation), efficient laser-based THz generation and the generation of high-order harmonics in gases. The availability of such a laser system allows the realization of a table-top coherent soft x-ray source emitting in the water window (e.g. 2.4-4.2 nm). This is an important step towards coherent imaging of living biological tissues. Another important application involves a seeding scheme of the Free Electron Laser currently under construction at PSI for achieving coherent hard x-ray radiation down to 1 nm wavelength range. Only coherent seeding allows the FEL to overcome spontaneous emission and to emit temporally coherent radiation. Seeding helps furthermore to stabilize the FEL pulse energy, spectrum and pulse duration. Many future FEL applications are going to profit from experimental conditions being identical for consecutive shots. Seeding has not been considered for (hard) x-ray FELs due to the lack of appropriate coherent soft x-ray seeding source. With the upgrade of our present laser system we expect to fullfill the requirements of an ideal seeding source.