NONLINEAR OPTICAL RESPONSE OF DOUBLY-RESONANT ALUMINUM NANOCLOCKS
Research output: Other conference contribution › Paper, poster or abstract › Professional
|Number of pages||1|
|Publication status||Published - 2017|
|Event||physics days 2017 - Aalto University Toolo Campus, Helsinki, Finland|
Duration: 22 Mar 2017 → 24 Mar 2017
|Conference||physics days 2017|
|Period||22/03/17 → 24/03/17|
responses less efficient. To overcome this low efficiency at the nanoscale, plasmonenhanced
nonlinear responses  using metallic nanoparticles have been proposed for
nonlinear optics. The important aspect here is that the localized surface plasmon
resonances (LSPRs) can concentrate incident light to strong local-fields (“hot spots”)
near the metal-dielectric interfaces. This is clearly favourable for driving nonlinear
optical responses, which scale with a high power of the optical field.
In this context and as proposed previously , doubly-resonant structures are very
promising for improving the nonlinear responses since they benefit from the field
enhancement at both excitation and emission wavelengths. To meet this condition, the
nanostructure or nanoparticle should be designed properly and the material well chosen.
Here, we show numerically that double resonances can boost the second-harmonic
generation (SHG) from a single aluminum (Al) nanoparticle. In order to avoid the
limitations due to the oxidation, heating and dissipative effects in the most common
plasmonic metals, e.g., gold and silver, recently Al has received wide interest as
excellent material for plasmonics .
We have studied both the linear and SHG responses of nanoclocks. A particle consists
of a disk with two different extended arms attached (e.g., nanorods). This structure
allows getting double resonances: one at the fundamental wavelength and the second at
the SHG wavelength. The numerical study highlights a particular geometry (75 nm for
the first arm and 35 nm for the second arm and a disk with diameter of 100 nm) with a
suitable linear response (around 1060 nm and 530 nm). We also verified that the localfield
distributions of at the fundamental and SHG wavelengths are spatially modematched
allowing efficient SHG radiation into the far field. Finally, the scattering cross
section for SHG was computed. Our results show that the SHG scattering is
significantly enhanced compared to a singly resonant particle when the fundamental and
SHG wavelengths coincide with the two plasmon resonances of the NC.
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 M. Celebrano et al, Nature Nanotechnology 10, 412 (2015).
 M. W. Knight et al, ACS Nano 8, 834 (2014).