The generation of ultrashort laser pulses down to few optical cycles in a very broad spectral region (from 100 nm up to the THz range) by nonlinear optical processes is a goal of most of the ongoing activities within the framework of this project. Besides the further improvement of known techniques for pulse shortening we also pursue several new strategies. In this context various nonlinear processes are studied in microstructure materials and microstructure fibers, such as supercontinuum generation and superfocusing.

Chirped Photonic Crystal Fibre (CPCF) for sub-20fs pulse delivery
a) Autocorrelation of a 13-fs pulse from a Ti:sapphire laser.
b) The same after propagation through 1.05 m of CPCF with 53-µm core size.
c) Autocorrelation for a 1.05-m-long piece of commercial HC800 fibre[SIB08]

In order to either generate new wavelengths or enhance the conversion efficiency, stability, spectral and spatial quality, and to simplify already existing concepts we investigate new solid-state nonlinear optical materials with 2^nd and 3^rd order nonlinear susceptibility and apply them in novel interaction schemes for frequency conversion of femtosecond pulses, e.g. chirped pulse optical parametric amplification (CPOPA). For tunable and efficient generation of sub-100 fs pulses in the wavelength range 100-160 nm we investigate, both experimentally and theoretically, four-wave-mixing in special hollow waveguides and compression of vacuum UV pulses by Raman-active molecular modulation.

Simultaneously with these activities devoted to the generation of ultrashort pulses with one or more extreme parameters we concentrate on the characterization of their temporal and spatial structure as well as on active control by shaping mechanisms. The full control over all parameters of ultrashort and few cycle light pulses (wavelength, temporal shape, phase, energy, etc.) is a long term objective for the whole project.

liquid crystal on silicon (LCOS) spatial light modulator (SLM) for high fidelity temporal pulse transfer .[BGD08]