arXiv subjects

Eugenio Di Gaetano

Publications and source records attributed to Eugenio Di Gaetano.

2 recordsLinked to original sources

arXiv2026

Second- and third-order nonlinearities in silicon nitride waveguides via heterogeneous integration of lithium niobate membranes

Thick, dispersion-engineered silicon nitride is a leading platform for integrated third-order nonlinear optics, supporting supercontinuum and frequency comb generation. However, it lacks the second-order nonlinearity required by many applications. Here we bond pre-fabricated x-cut thin-film lithium niobate membranes onto finished silicon nitride waveguides as a back-end step, compatible with commercially fabricated waveguides. A single silicon nitride waveguide generates an octave-spanning supercontinuum and, through the lithium niobate membrane, concurrent second-harmonic, sum- and difference-frequency generation. These results open new possibilities for thick silicon nitride photonics, from visible light generation to on-chip $f$-$2f$ comb self-referencing, a key step towards miniaturised timing and navigation quantum technologies.

physics.optics↗

arXiv2020

Picosecond Ultrasonics with Miniaturized Semiconductor Lasers

There is a great desire to extend ultrasonic techniques to the imaging and characterization of nanoobjects. This can be achieved by picosecond ultrasonics, where by using ultrafast lasers it is possible to generate and detect acoustic waves with frequencies up to terahertz and wavelengths down to nanometers. In our work we present a picosecond ultrasonics setup based on miniaturized mode-locked semiconductor lasers, whose performance allows us to obtain the necessary power, pulse duration and repetition rate. Using such a laser, we measure the ultrasonic echo signal with picosecond resolution in a Al film deposited on a semiconductor substrate. We show that the obtained signal is as good as the signal obtained with a standard bulky mode-locked Ti-Sa laser. The experiments pave the way for designing integrated portable picosecond ultrasonic setups on the basis of miniaturized semiconductor lasers.

physics.app-ph↗