Selectively addressing optically nonlinear nanocrystals by polarization-shaped ultrafast laser pulses

摘要

A noncentrosymmetric nanocrystal can produce second-harmonic generation (SHG) and sum-frequency generation (SFG) upon interaction with a laser field. The SHG or SFG radiation depends on the orientation of the nanocrystal as well as the field polarization, which allows for modulating the second-order emission of an arbitrarily oriented nanocrystal by specially tailoring the field polarization. We theoretically study SHG and SFG signals produced by nanocrystals driven with broad-bandwidth laser pulses. Several simulations explore the influence of the field polarization and temporal pulse profile. The latter two factors are decoupled in their influence upon the SHG and SFG signals, and thus polarization and temporal shaping can be independently performed to modulate a nanocrystals' second-order emission. We consider the possibility of enhancing (suppressing) the signal from one nanocrystal among others by choosing the appropriate polarization, thereby opening up the prospect of selectively addressing optically nonlinear nanocrystals.