2,605 research outputs found
Surface enhanced Raman spectroscopy using a single mode nanophotonic-plasmonic platform
Surface Enhanced Raman Spectroscopy (SERS) is a well-established technique
for enhancing Raman signals. Recently photonic integrated circuits have been
used, as an alternative to microscopy based excitation and collection, to probe
SERS signals from external metallic nanoparticles. However, in order to develop
quantitative on-chip SERS sensors, integration of dedicated nanoplasmonic
antennas and waveguides is desirable. Here we bridge this gap by demonstrating
for the first time the generation of SERS signals from integrated bowtie
nanoantennas, excited and collected by a single mode waveguide, and rigorously
quantify the enhancement process. The guided Raman power generated by a
4-Nitrothiophenol coated bowtie antenna shows an 8 x 10^6 enhancement compared
to the free-space Raman scattering. An excellent correspondence is obtained
between the theoretically predicted and observed absolute Raman power. This
work paves the way towards fully integrated lab-on-a-chip systems where the
single mode SERS-probe can be combined with other photonic, fluidic or
biological functionalities.Comment: Submitted to Nature Photonic
Transport and optical response of molecular junctions driven by surface plasmon-polaritons
We consider a biased molecular junction subjected to external time-dependent
electromagnetic field. The field for two typical junction geometries (bowtie
antennas and metal nanospheres) is calculated within finite-difference
time-domain technique. Time-dependent transport and optical response of the
junctions is calculated within non-equilibrium Green's function approach
expressed in a form convenient for description of multi-level systems. We
present numerical results for a two-level (HOMO-LUMO) model, and discuss
influence of localized surface plasmon polariton modes on transport.Comment: 9 pages, 6 figure
Antenna-coupled silicon-organic hybrid integrated photonic crystal modulator for broadband electromagnetic wave detection
In this work, we design, fabricate and characterize a compact, broadband and
highly sensitive integrated photonic electromagnetic field sensor based on a
silicon-organic hybrid modulator driven by a bowtie antenna. The large
electro-optic (EO) coefficient of organic polymer, the slow-light effects in
the silicon slot photonic crystal waveguide (PCW), and the broadband field
enhancement provided by the bowtie antenna, are all combined to enhance the
interaction of microwaves and optical waves, enabling a high EO modulation
efficiency and thus a high sensitivity. The modulator is experimentally
demonstrated with a record-high effective in-device EO modulation efficiency of
r33=1230pm/V. Modulation response up to 40GHz is measured, with a 3-dB
bandwidth of 11GHz. The slot PCW has an interaction length of 300um, and the
bowtie antenna has an area smaller than 1cm2. The bowtie antenna in the device
is experimentally demonstrated to have a broadband characteristics with a
central resonance frequency of 10GHz, as well as a large beam width which
enables the detection of electromagnetic waves from a large range of incident
angles. The sensor is experimentally demonstrated with a minimum detectable
electromagnetic power density of 8.4mW/m2 at 8.4GHz, corresponding to a minimum
detectable electric field of 2.5V/m and an ultra-high sensitivity of
0.000027V/m Hz^-1/2 ever demonstrated. To the best of our knowledge, this is
the first silicon-organic hybrid device and also the first PCW device used for
the photonic detection of electromagnetic waves. Finally, we propose some
future work, including a Teraherz wave sensor based on antenna-coupled
electro-optic polymer filled plasmonic slot waveguide, as well as a fully
packaged and tailgated device.Comment: 20 pages, 16 figure
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