Tampere University of Technology

TUTCRIS Research Portal

Coherent nonlinear emission from a single KTP nanoparticle with broadband femtosecond pulses

Research output: Contribution to journalArticleScientificpeer-review


Original languageEnglish
Pages (from-to)4652-4658
Number of pages7
JournalOptics Express
Issue number6
Publication statusPublished - 16 Mar 2009
Externally publishedYes
Publication typeA1 Journal article-refereed


We demonstrate that the intensity of the second harmonic (SH) generated in KTiOPO4 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-tonoise 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.