G. Cerullo

Coherent Vibrational Dynamics

Time Domain Vibrational Spectroscopy: Principle and Experimental Tools,G. Cerullo and C. Manzoni Coherent Dynamics of Hydrogen Bonds in Liquids Studied by Femtosecond Vibrational Spectroscopy,T. Elsaesser Coherent Phonon Dynamics in pi-Conjugated Chains,G. Lanzani Coherent Phonons in Bulk and Low-Dimensional Semiconductors,M. Forst and T. Dekorsy Coherent Dynamics of Halogen Molecules in Rare Gas Solids,M. Guhr Coherent Vibrational Dynamics of Exciton Self-Trapping in Quasi-One-Dimensional Systems,S.L. Dexheimer Index

Sub-two-cycle light pulses at 1.6 μm from an optical parametric amplifier

We generate 8.5 fs pulses at 1.6 mm from an 800-nm-pumped optical parametric amplifier working at degeneracy, employing a deformable mirror compressor. These are the shortest light pulses in this wavelength range.

Resonator Designs for High Brightness Solid-State Lasers

The generation of diffraction limited beams of high power or energy represents a research field of great interest for many scientific and industrial applications. Laser materials of large volume are available and design procedures for optical resonators with large cross-sectional area fundamental modes, that can exploit the laser medium, are a demanding problem. Stable resonators operating on the fundamental TEM00 mode produce high quality diffraction limited beams; however, the transverse mode dimension and, as a consequence, the extracted energy from the gain medium are generally small. On the other hand, unstable resonators can sustain fundamental modes of wide crosssection, but the output beam quality and divergence can be degraded by the spatial profile of the output beam.

Erbium-Ytterbium doped active waveguides at 1.5 μm made by femtosecond micromaching

We demonstrated low-loss (<0.25 dB/cm), gaussian-mode profile single-transverse mode active waveguides at 1.5 μm in Er:Yb-doped glass substrate made by femtosecond micromachining. Net gain has been achieved when used as active element in a standard waveguide-amplifier set-up.

Spatial and spectral properties of high-order harmonics in the few-optical-cycle regime

Summary form only given. The recent availability of high-peak-power few-optical-cycle light pulses has opened the way to the investigation of light-matter interaction in the strong-field regime with unprecedented temporal resolution. In particular high-order harmonic generation in the few-optical-cycle regime is attractive for the generation of soft-x-ray pulses with duration down to the sub-femtosecond range. In this work we present both an experimental and a theoretical analysis of harmonic generation with sub-10-fs light pulses obtained using the hollow-fiber compression technique. To observe the harmonic emission we used a high-resolution x-ray spectrometer, based on a chirped grating and a high-resolution CCD detector.

Charge carrier generation in a conjugated polymer studied via ultrafast pump-push-probe experiments

Summary form only given. Conjugated polymers find rapidly growing application in electroluminescent displays and are extensively studied for use in photovoltaics and laser diodes. For a wide range of conjugated materials ultrafast pump-probe experiments have revealed the excited state dynamics of singlet and triplet excitons as well as positively and negatively charged polarons. Charge carriers play a key role in all the above mentioned applications. However, there is yet no clear picture of the mechanisms which lead to their generation.Photocurrent excitation cross-correlation measurement. on methyl-substituted ladder-type poly(para)phenyl (m-LPPP), a prototypical conjugated polymer with very appealing properties for the above mentioned applications, have suggested that charge carrier generation occurs preferentially from higher lying states during energy migration. Our approach to examining this mechanism consists of an innovative modification of the ultrafast time-resolved pump-probe technique.

Highly compact sub-10-fs optical parametric amplifier in the visible

Summary form only given. We report on a compact noncollinear visible OPA with a compressor made exclusively of chirped mirrors. We employ ultra-broadband chirped mirrors of novel design which allow us to achieve group delays (GDs) varying nearly linearly with frequency over bandwidths in excess of100 THz. The use of the chirped mirrors results in a simple and reliable system for the generation of tunable sub-lO-fs pulses in the visible spectral range.

Ultrafast Dynamics of Field-Induced Charge Photogeneration in Conducting Polymers

We performed field-assisted time-resolved femtosecond pump-probe experiments in light emitting diodes of laddertype poly-(para-phenylene). Field-induced charge carriers generation is directly observed monitoring the characteristic polaron absorption band at 1.91 eV. Charge carriers are directly formed by singlet exciton dissociation in the picosecond time domain.

Mode-Locking of Solid State Lasers by Cascaded Second Order Nonlinearities

In the last years considerable efforts have been devoted to the development of new passive mode-locking (ML) techniques for cw picosecond solid-state lasers exploiting fast nonlinearities. For Nd:YAG and Nd:YLF the most successful techniques up to now have been Additive Pulse ML1, Kerr Lens ML2 and Antiresonant Fabry-Perot Saturable Absorber ML based on absorption saturation in semiconductors. Pulses with duration below 10 ps have been obtained from Nd:YAG and Nd:YLF lasers mode-locked using these techniques. Together with their well known advantages these methods present some drawbacks: additive pulse ML requires a very accurate interferometric control of the cavity length, Kerr-lens ML shows weak tendency to self-starting, semiconductor saturable absorbers are rather difficult to fabricate.