Coherent nonlinear emission from a single KTP nanoparticle with broadband femtosecond pulses.
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.
Wnuk
Pawel
P
Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warsaw, Poland. ptwnuk@fuw.edu.pl
Xuan
Loc Le
LL
Slablab
Abdallah
A
Tard
Cédric
C
Perruchas
Sandrine
S
Gacoin
Thierry
T
Roch
Jean-François
JF
Chauvat
Dominique
D
Radzewicz
Czesław
C