11 Plasmonic Functionalities Based on Detuned Electrical Dipoles
419
(a)
(b)
(c)
Fig. 11.9 a Representative SEM-image of the DED grating with Θ x =400 nm and Θ y =750 nm along
with b experimental and c simulated transmission spectra of individual nanorod arrays (blue and
red curves) and arrays with pairs of nanorods (black curves). The experimentally obtained spectra
of the array with pairs of nanorods were measured before and after deposition of a PMMA phasematching layer, whereas the simulated spectra was obtained with the nanorods embedded in glass.
The gold nanorods have 50 nm × 50 nm cross sections and lengths 90 and 140 nm, respectively.
Adapted with permission from Ref. [14]. ©2011 American Chemical Society
broad band halogen light source with a fiber output whose (weakly divergent) radiation was directed (at normal incidence) through a polarizer on the fabricated arrays
of nanorods aligned so that their axes were parallel to the light polarization. The
transmitted radiation was collected with an objective and fed into an optical fiber
connected to a spectrometer. The transmission spectra were measured before and
after depositing a thick (several micrometers) layer of PMMA. The latter was used
to form a homogeneous dielectric environment for gold nanorods. The transmission
spectra obtained with arrays of nanorod pairs before and after the deposition of the
PMMA layer feature local maxima located at ∼755 and ∼790 nm, respectively, each
being surrounded by two local minima (Fig. 11.9b). These maxima indicate the suppression of scattering achieved at the wavelengths that are intermediate with respect
to the resonance wavelengths of individual nanorods. The effect of enhanced transmission is especially pronounced and documented in detail for the arrays covered
with the PMMA layer: the transmission spectra obtained with the arrays of individual short and long nanorods exhibit the effect of detuning in their resonances
located at wavelengths ∼720 nm and 860 nm, while the transmission spectrum of
the array consisting of pairs of corresponding nanorods (Fig. 11.9a) shows the effect
of increased transmission at the intermediate wavelength of ∼790 nm (Fig. 11.9b).
Note also a significant red shift in the transmission spectrum of the DED array after
the deposition of the PMMA layer (due to a change in the dielectric environment of
nanorods), as well as an improvement in the contrast. We have attempted to model
419
(a)
(b)
(c)
Fig. 11.9 a Representative SEM-image of the DED grating with Θ x =400 nm and Θ y =750 nm along
with b experimental and c simulated transmission spectra of individual nanorod arrays (blue and
red curves) and arrays with pairs of nanorods (black curves). The experimentally obtained spectra
of the array with pairs of nanorods were measured before and after deposition of a PMMA phasematching layer, whereas the simulated spectra was obtained with the nanorods embedded in glass.
The gold nanorods have 50 nm × 50 nm cross sections and lengths 90 and 140 nm, respectively.
Adapted with permission from Ref. [14]. ©2011 American Chemical Society
broad band halogen light source with a fiber output whose (weakly divergent) radiation was directed (at normal incidence) through a polarizer on the fabricated arrays
of nanorods aligned so that their axes were parallel to the light polarization. The
transmitted radiation was collected with an objective and fed into an optical fiber
connected to a spectrometer. The transmission spectra were measured before and
after depositing a thick (several micrometers) layer of PMMA. The latter was used
to form a homogeneous dielectric environment for gold nanorods. The transmission
spectra obtained with arrays of nanorod pairs before and after the deposition of the
PMMA layer feature local maxima located at ∼755 and ∼790 nm, respectively, each
being surrounded by two local minima (Fig. 11.9b). These maxima indicate the suppression of scattering achieved at the wavelengths that are intermediate with respect
to the resonance wavelengths of individual nanorods. The effect of enhanced transmission is especially pronounced and documented in detail for the arrays covered
with the PMMA layer: the transmission spectra obtained with the arrays of individual short and long nanorods exhibit the effect of detuning in their resonances
located at wavelengths ∼720 nm and 860 nm, while the transmission spectrum of
the array consisting of pairs of corresponding nanorods (Fig. 11.9a) shows the effect
of increased transmission at the intermediate wavelength of ∼790 nm (Fig. 11.9b).
Note also a significant red shift in the transmission spectrum of the DED array after
the deposition of the PMMA layer (due to a change in the dielectric environment of
nanorods), as well as an improvement in the contrast. We have attempted to model