A. Cybo-Ottone

On the stability, mode properties, and misalignment sensitivity of femtosecond dye laser resonators

Abstract General analytic expressions concerning optical stability, mode spot size in the gain and saturable absorber jets, and misalignment sensitivity of femtosecond dye laser resonators are derived by using the one-way ABCD ray matrix technique. The results, confirmed by a few preliminary experiments, are valid for any resonator configuration and set the bases for new criteria in resonator design.

Highly stable 60 fs pulses from a cavity dumped hybridly mode-locked dye laser

Abstract We report on a new resonator configuration for a cavity dumped hybridly mode-locked dye laser which allows the generation of extremely stable pulses as short as 60 fs. This is a demonstration of the superior performance of low misalignment sensitivity resonators compared to traditional nearly confocal configurations.

Femtosecond and picosecond excition dynamics in poly-alkoxy-thiophene and poly-alkoxy-thiophene—vinylene

Abstract We report on transient saturated absorption measurements on poly (3-pentoxy-thiophene) and poly (3-pentoxy-thiophene—vinylene) by the femtosecond pump and probe technique investigating exciton relaxation dynamics. The photoinduced bleachings can be fitted by a fast biexponential decay followed in some cases by a power law decay. The initial part of the decay is consistent with the self-trapped exciton relaxation processes. The presence of the power law is strictly related to the appearance of a long wavelength tail in the absorption spectra.

Femtosecond broadband absorption spectroscopy of photodissociating molecules

We have tried to present a picture of what is conceptually involved in our studies thus far. The major finding has been the observation that two widely different types of transient absorption spectra are to be seen in nature, the type we call “impact spectra”, and the type we term “statistical spectra”. Both types, when interpreted and analyzed properly, can provide information about difference potentials.

Nonlinear mirror mode-locking of cw Nd lasers

ding/core interface, depending on the energy flux in the interface region. We discuss these results in terms of colour center formation and of possible thermal or stress-induced effects. In conclusion, careful choice of coupling conditions is necessary for UV-laser based fiber optical sensors to avoid undesirable photodegradation. Selection of laser parameters like laser energy and repetition rate for a given application has to take into account the dependence of fiber transmission on these parameters.

Femtosecond pump and probe experiments on thiophene-based polymers by a hybridly mode-locked cavity-dumped dye laser

Results on the bleaching decay observed in low-band gap thiophene-based polymers by femtosecond pump and probe experiments are presented. The laser used for excitation and probe is a newly developed cavity dumped femtosecond dye laser. The excited state kinetics of these materials presents a fast biexponential time behavior that may be related to the formation and decay of self-trapped excitons. >

Novel resonator design for femtosecond lasers

We present a general analysis of resonators with multiple foci. The optical stability is characterized by means of a simple analytical formulation. An analysis of the sensitivity of the resonator to external perturbations in terms of misalignment sensitivity, defines new criteria in the resonator design, which provide new configurations different from the traditional nearly confocal ones. A few experiments on a resonator configuration with low misalignment sensitivity for hybridly mode-locked dye lasers are reported. The problem of pulse stabilization for these lasers is also considered.