Nonlinear spectroscopy and structured matter

                     Group Leader: Domenico Paparo

THZ


 

We investigate various aspects of light-matter interaction by using ultrafast (femtoseconds) intense laser pulses, with particular emphasis on spatially structured systems. The processes that are nonlinear in the optical field add new potentialities to standard optical spectroscopy, which has always been an invaluable experimental tool for elucidating fundamental mechanisms in soft and condensed matter physics. For instance, by exploiting second-order processes we investigate surface and interface properties with sub-nanometer resolution (second harmonic generation - SHG). Another example is given by two colors Four-Wave-Mixing in air, which we exploit to coherently generate broad-band single-cycle THz pulses, so to expand our spectroscopic capability to the very-far infrared region. The THz pulses generated in this way are extremely intense, thus enabling the observation of nonlinear optical effects until now investigated only in the visible range of the electromagnetic spectrum. This is the case of the coherent THz Hyper-Raman (THYR) effect, which we have very recently discovered (see figure). 

We apply our spectroscopic tools to a large variety of materials with a special focus in recent years on the hetero-structures of strongly correlated transition-metal oxides, ultrathin ferroelectric films, laser-treated diamond for THz applications and ionic liquids. We are also interested in developing spatially structured ultrafast pulses and studying their interaction with matter.

 

Publications

All-carbon THz components based on laser-treated diamond
S. Amoruso, A. Andreone, A. Bellucci, C. Koral, M. Girolami, M. Mastellone, S. Mou, S. Orlando, G. P. Papari, D. Paparo, R. Polini, A. Rubano, A. Santagata, V. Serpente, V. Valentini, D. M. Trucchi, Carbon 163, 197-201 (2020).

Optical second harmonic generation from LaAlO3/SrTiO3 interfaces with different in-plane anisotropies
A. Rubano, M. Scigaj, F. Sanchez, G. Herranz, D. Paparo, J. Phys.: Condens. Matter 32, 135001 (2020).

Coherent THz Hyper-Raman: Spectroscopy and Application in THz Detection
A. Ceraso, S. Mou, A. Rubano, D. Paparo, Materials 12, 3870 (2019)

Terahertz hyper-Raman time-domain spectroscopy of gallium selenide and its application in terahertz detection
S. Mou, A. Rubano, D. Paparo, Appl. Phys. Lett. 115, 211105 (2019).

Terahertz Hyper-Raman Time-Domain Spectroscopy
A. Rubano, S. Mou, L. Marrucci, D. Paparo, ACS Photonics 6, 1515-1523 (2019).

Q-plate technology: a progress review
A. Rubano, F. Cardano, B. Piccirillo, L. Marrucci, J. Opt. Soc. Am. B 36, D70 (2019).

Vector vortex beams generated by q-plates as a versatile route to direct fs laser surface structuring
J. JJ Nivas, E. Allahyari, F. Cardano, A. Rubano, R. Fittipaldi, A. Vecchione, D. Paparo, L. Marrucci, R. Bruzzese, S. Amoruso, Appl. Surf. Sci. 471, 1028–1033 (2019).

Surface structures with unconventional patterns and shapes generated by femtosecond structured light fields
J. JJ Nivas, E. Allahyari, F. Cardano, A. Rubano, R. Fittipaldi, A. Vecchione, D. Paparo, L. Marrucci, R. Bruzzese, S. Amoruso, Sci. Rep. 8, 13613 (2018).

Simple method for the characterization of intense Laguerre-Gauss vector vortex beams
E. Allahyari, J. JJ. Nivas, F. Cardano, R. Bruzzese, R. Fittipaldi, L. Marrucci, D. Paparo, A. Rubano, A. Vecchione, S. Amoruso, Appl. Phys. Lett. 112, 211103 (2018).

Monitoring the interfacial electric field in pure and doped SrTiO3 surfaces by means of phase-resolved optical second harmonic generation
A. Rubano, S. Mou, D. Paparo, Optics and lasers in engineering 104, 300-303 (2018).

Broadband Terahertz Spectroscopy of Imidazolium-Based Ionic Liquids
S. Mou, A. Rubano, D. Paparo, J. Phys. Chem. B 122, 3133-3140 (2018).

Ultrafast Modification of the Polarity at LaAlO3/SrTiO3 Interfaces
A. Rubano, T. Günter, M. Fiebig, F. Miletto Granozio, L. Marrucci, D. Paparo, Phys. Rev. B 97, 035438 (2018).

Femtosecond laser surface structuring of silicon with Gaussian and optical vortex beams
J. J. Nivas, S. T. He, Z. M. Song, A. Rubano, A. Vecchione, D. Paparo, L. Marrucci, R. Bruzzese, S. Amoruso, Appl. Surf. Sci. 418, 565-571 (2017).

Complex Permittivity of Ionic Liquid Mixtures Investigated by Terahertz Time-Domain Spectroscopy
S. Mou, A. Rubano, D. Paparo, J. Phys. Chem. B 121, 7351-7358 (2017).

Surface Structuring with Polarization-Singular Femtosecond Laser Beams Generated by a q-plate
J. JJ Nivas, F. Cardano, Z. Song, A. Rubano, R. Fittipaldi, A. Vecchione, D. Paparo, L. Marrucci, R. Bruzzese, S. Amoruso, Sci. Rep. 7, 40795 (2017).