We demonstrate a composite metamaterial composed of two asymmetrically oriented π-shaped structures that
exhibits plasmonic analogue of electromagnetically induced transparency (EIT). The structure exhibits fine
tuning of EIT-like spectral behavior and spatial control of near-field intensity distribution. Originated from the
asymmetric design, we introduce a more compact system which possesses the similar EIT-like spectral response
as well as much smaller optical mode volumes.
KEYWORDS: Plasmonics, Lithography, Nanolithography, Electron beam lithography, Photomasks, Metamaterials, Antennas, Fabrication, Near field optics, Nanorods
We demonstrate a novel fabrication approach for high-throughput fabrication of engineered plasmonic antenna arrays
and metamaterials with Nanostencil Lithography (NSL). NSL technique, relying on deposition of materials through a
shadow mask, offers the flexibility and the resolution to fabricate radiatively engineer nanoantenna arrays for excitation
of collective plasmonic resonances. We confirmed that the antenna arrays fabricated by NSL shows high optical quality
similar to EBL fabricated ones. Furthermore, we show nanostencils can be reused multiple times to fabricate selfsame
structures with identical optical responses repeatedly and reliably. This capability is particularly useful when highthroughput
replication of the optimized nanoparticle arrays is desired. In addition to its high-throughput capability, NSL
permits single step nanofabrication of plasmonic devices on surfaces that are difficult to work with electron/ion beam
techniques. Nanostencil lithography is a resist free process thus allows the transfer of the nanopatterns to any planar
substrate whether it is conductive, insulating or magnetic. As proof of the versatility of the NSL technique, we show
fabrication of plasmonic structures and metamaterials in variety of geometries. In metamaterial and plasmonic devices,
unique geometries with small gaps and asymmetries can induce novel electromagnetic responses such as plasmon
induced transparency and also giant near-field intensities that are important for enhanced vibrational spectroscopy and
non-linear optics applications. This nanofabrication scheme, enabling the reusability of stencil and offering flexibility on
the substrate choice and nano-pattern design could significantly enhance wide-use of plasmonics in sensing technologies.1
KEYWORDS: Antennas, Metamaterials, Nanolithography, Near field optics, Transmittance, Metals, Electron beam lithography, Nanostructures, Near field, Optical resolution
The subject of light transmission through optically thin metal films perforated with arrays of subwavelength nanoholes
has recently attracted significant attention. In this work, we present experimental and calculated results on optical
transmission/reflection of the U-shaped nanoapertures for enhanced optical transmission and resolution. We propose
different structure designs in order to prove the effect of geometry on resonance and enhanced fields. Theoretical
calculations of transmission/reflection spectra and field distributions of U-shaped nano-apertures are performed by using
3-dimensional finite-difference time-domain method. The results of these numerical calculations show that transmission
through the apertures is indeed concentrated in the gap region. Added to theoretical calculations we also performed a liftoff
free plasmonic device fabrication technique based on positive resist electron beam lithography and reactive ion
etching in order to fabricate U-shaped nanostructures. After transferring nanopattern on 80 nm thick suspended SiNx
membrane using EBL followed by dry etching, a directional metal deposition processes is used to deposit 5 nm thick Ti
and 30 nm thick Au layers. Theoretical calculations are supported with experimental results to prove the tunability of
resonances with the geometry at the mid-infrared wavelengths which could be used for infrared detection of
biomolecules.
KEYWORDS: Plasmonics, Nanolithography, Lithography, Electron beam lithography, Antennas, Photomasks, Fabrication, Near field optics, Nanostructures, Nanorods
We demonstrate a novel fabrication approach for high-throughput fabrication of engineered infrared plasmonic nanorod
antenna arrays with Nanostencil Lithography (NSL). NSL technique, relying on deposition of materials through a
shadow mask, offers the flexibility and the resolution to fabricate radiatively engineer nanoantenna arrays for excitation
of collective plasmonic resonances. Overlapping these collective plasmonic resonances with molecular specific
absorption bands can enable ultrasensitive vibrational spectroscopy. First, nanorod antenna arrays fabricated using NSL
are investigated using SEM and optical spectroscopy, and compared against the nanorods with the same dimensions
fabricated using EBL. No irregularities on the periodicity or the physical dimensions are detected for NSL fabricated
nanorods. We also confirmed that the antenna arrays fabricated by NSL shows high optical quality similar to EBL
fabricated ones. Furthermore, we show nanostencils can be reused multiple times to fabricate selfsame structures with
identical optical responses repeatedly and reliably. This capability is particularly useful when high-throughput replication
of the optimized nanoparticle arrays is desired. In addition to its high-throughput capability, NSL permits fabrication of
plasmonic devices on surfaces that are difficult to work with electron/ion beam techniques. Nanostencil lithography is a
resist free process thus allows the transfer of the nanopatterns to any planar substrate whether it is conductive, insulating
or magnetic. As proof of the versatility of the NSL technique, we show fabrication of plasmonic structures in variety of
geometries. We also demonstrate that nanostencil lithography can be used to achieve functional plasmonic devices in a
single fabrication step, on variety of substrates. We introduced NSL for fabrication of nanoplasmonic structures
including antenna arrays on rigid surfaces such as silicon, CaF2 and glass. In conclusion, Nanostencil Lithography
enables plasmonic substrates supporting spectrally narrow far-field resonances with enhanced near-field intensities
which are very useful for vibrational spectroscopy. We believe this nanofabrication scheme, enabling the reusability of
stencil and offering flexibility on the substrate choice and nano-pattern design could significantly enhance wide-use of
plasmonics in sensing technologies.
We demonstrate a novel fabrication approach for high-throughput fabrication of engineered infrared plasmonic nanorod
antenna arrays with nanostencil lithography (NSL). NSL technique, relying on deposition of materials through a shadow
mask, offers the flexibility and the resolution to radiatively engineer nanoantenna arrays for excitation of collective
plasmonic resonances. As stencil, we use suspended silicon nitride membrane patterned with nanoapertures and fabricate
nanorod antenna arrays. Our spectral measurements and electron microscopy images faithfully confirm the feasibility of
NSL technique for large area patterning of nanorod antenna arrays with optical qualities achievable by electron-beam
lithography. Furthermore, we show nanostencils can be reused multiple times to fabricate same structures repeatedly and
reliably with identical optical responses. This capability is particularly useful when high-throughput replication of the
optimized nanoparticle arrays is desired. In addition to its high-throughput capability, NSL permits fabrication of
plasmonic devices on surfaces that are difficult to work with electron/ion beam techniques. Nanostencil lithography is a
resist free process thus allows the transfer of the nanopatterns to any planar substrate whether it is conductive, insulating
or magnetic. As proof of the versatility of the NSL technique, by simply changing the aperture pattern on the silicon
nitride membrane, we show fabrication of plasmonic structures in variety of geometries and on different substrates.
Nanostencil Lithography enables fabrication of plasmonic substrates supporting spectrally narrow far-field resonances
with enhanced near-field intensities. Overlapping these collective plasmonic resonances with molecular specific
absorption bands can enable ultrasensitive vibrational spectroscopy.
Performances of surface biosensors are often controlled by the analyte delivery rate to the sensing surface instead of
sensors intrinsic detection capabilities. In a microfluidic channel, analyte transports diffusively to the biosensor surface
severely limiting its performance. At low concentrations, this limitation, commonly known as mass transport problem,
causes impractically long detection times extending from days to months. In this proceeding, we propose and
demonstrate a hybrid biosensing platform merging nanoplasmonics and nanofluidics. Unlike conventional approaches
where the analytes simply stream pass over the sensing surface, our platform enables targeted delivery of analytes to the
sensing surface. Our detection platform is based on extraordinary light transmission effect (EOT) in suspended
plasmonic nanohole arrays. The subwavelength size nanoholes here act as nanofluidic channels connecting the
microfluidic chambers on both sides of the sensors. In order to materialize our detection platform, we also introduce a
novel multilayered micro/nanofluidics scheme allowing three dimensional control of the fluidic flow. Using our
platform, we show 14-fold improvement in mass transport rate constant appearing in the exponential term. To fabricate
these biosensors, we also introduce a lift-off free plasmonic device fabrication technique based on positive resist electron
beam lithography. Simplicity of this fabrication technique allows us to fabricate nanostructures with ease, high
yield/reproducibility and minimal surface roughness. As a result, we achieve higher refractive index sensitivities. This
fabrication technique can find wide range of applications in nanoplasmonics field by eliminating the need for
operationally slow and expensive focused ion beam lithography.
In this work, we are demonstrating resonant light transmission through hybrid multi-layered plasmonic crystals, which
are formed by a coupled nanohole and a nanoparticle array. This structures are shown to provide the conventional
extraordinary optical transmission (EOT) peaks and also a newly found cavity-based mode is introduced with an
emphasis to its high sensing capabilities. Plasmon hybridization in coaxial nanocavities is also addressed, where the
nanohole array and the nanoparticle array are in the same layer.
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