Biomedical subjects

Roberta Ramponi

Publications and source records attributed to Roberta Ramponi.

3 recordsLinked to original sources

PubMed2006

Group-velocity control by quadratic nonlinear interactions.

We give direct experimental evidence that the group velocity of ultrashort pulses can be controlled through chi(2)-cascaded interactions, under the condition of large group-velocity mismatch. The group velocity can be finely tuned by acting on pulse intensity and phase mismatch. Group-delay shifts up to 50 fs are achieved by propagating 40 fs pulses around 1400 nm in a 25 mm long periodically poled stoichiometric lithium tantalate crystal.

Journal Article↗

PubMed2005

Measurement of the nonlinear phase shift induced by cascaded interactions in a periodically poled lithium niobate waveguide.

We report on the measurement of nonlinear phase shift phiNL induced by a strong pump at wavelength lamda p on a weak signal at lamda s through a cascade of two second-order interactions in a periodically poled lithium-niobate waveguide. The experiment is performed by use of an interferometric scheme especially designed to be insensitive to slow mechanical and thermal drift effects. The observed behavior of phiNL as a function of pump power and of wavelength difference lamda p - lamda s, is in good agreement with the theoretical predictions.

Journal Article↗

PubMed2004

Optical waveguide writing with a diode-pumped femtosecond oscillator.

Optical waveguide writing is demonstrated by means of a diode-pumped cavity-dumped Yb:glass femtosecond laser oscillator with a pulse energy of 270 nJ at a 166-kHz repetition rate. Waveguides realized on an Er:Yb-doped phosphate glass are almost perfectly mode matched to standard single-mode fibers at 1.55 microm and show a 1.2-dB net gain in a standard telecommunications amplifier setup. Waveguide writing with a compact femtosecond laser oscillator is an important step toward introducing this technique into an industrial context.

Journal Article↗