title: Coherent nonlinear emission from a single KTP nanoparticle with broadband femtosecond pulses.
abstract: We demonstrate that the intensity of the second harmonic (SH) generated in KTiOPO(4) nanoparticles excited with femtosecond laser pulses increases with decreasing duration of the infrared pump pulses. The SH intensity scales, approximately, as the inverse of the laser pulse duration ranging between 13 fs and 200 fs. The SH intensity enhancement requires careful compensation of the high-order spectral phase, being achieved with a genetic algorithm. Using ultrashort laser pulses improves the signal-to-noise ratio and will allow the detection of 10-nm size particles. Finally, we demonstrate that the spectrum of broadband (100 nm) pulses can be shaped to generate non-degenerate sum-frequency mixing. This opens up access to the polarization degrees of freedom of this second-order nonlinear process at the nanoscale.
authors.affiliation: Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warsaw, Poland. ptwnuk@fuw.edu.pl
authors.forename: Pawel
authors.initials: P
authors.lastname: Wnuk
authors.forename: Loc Le
authors.initials: LL
authors.lastname: Xuan
authors.forename: Abdallah
authors.initials: A
authors.lastname: Slablab
authors.forename: Cédric
authors.initials: C
authors.lastname: Tard
authors.forename: Sandrine
authors.initials: S
authors.lastname: Perruchas
authors.forename: Thierry
authors.initials: T
authors.lastname: Gacoin
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Roch
authors.forename: Dominique
authors.initials: D
authors.lastname: Chauvat
authors.forename: Czesław
authors.initials: C
authors.lastname: Radzewicz