Selective excitation of individual nanoantennas by pure spectral phase control in the ultrafast coherent regime

Nanophotonics

article

Nicolò Accanto¹  Pablo M. de Roque¹  Marcial Galvan-Sosa³  Ion M. Hancu¹  Niek F. van Hulst¹ 

[1] ICFO—Institut de Ciences Fotoniques, The Barcelona Institute of Science & Technology;Institut de la Vision, Sorbonne Université;Neurochemistry and Neuroimaging Laboratory, University of La Laguna;ICREA—Institució Catalana de Recerca i Estudis Avançats

关键词: closed-loop control;    coherent control;    hot spot;    nanoantenna;    spectral phase control;    ultrafast;   

DOI  :  10.1515/nanoph-2020-0406

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

Coherent control is an ingenious tactic to steer a system to a desired optimal state by tailoring the phase of an incident ultrashort laser pulse. A relevant process is the two-photon–induced photoluminescence (TPPL) of nanoantennas, as it constitutes a convenient route to map plasmonic fields, and has important applications in biological imaging and sensing. Unfortunately, coherent control of metallic nanoantennas is impeded by their ultrafast femtosecond dephasing times so far limiting control to polarization and spectral optimization. Here, we report that phase control of the TPPL in resonant gold nanoantennas is possible. We show that, by compressing pulses shorter than the localized surface plasmon dephasing time (<20 fs), a very fast coherent regime develops, in which the two-photon excitation is sensitive to the phase of the electric field and can therefore be controlled. Instead, any phase control is gone when using longer pulses. Finally, we demonstrate pure phase control by resorting to a highly sensitive closed-loop strategy, which exploits the phase differences in the ultrafast coherent response of different nanoantennas, to selectively excite a chosen antenna. These results underline the direct and intimate relation between TPPL and coherence in gold nanoantennas, which makes them interesting systems for nanoscale nonlinear coherent control.

【 授权许可】

CC BY