27,473 research outputs found
Surface Accuracy Measurement Sensor for Deployable Reflector Antennas (SAMS DRA)
Specifications, system configurations, and concept tests for surface measurement sensors for deployable reflector antennas are presented. Two approaches toward the optical measurement of remote target displacements are discussed: optical ranging, in which the basic measurement is target-to-sensor range; and in particular, optical angular sensing, in which the principle measurements are of target angular displacements lateral to the line of sight. Four representative space antennas are examined
Seebeck Nanoantennas for Infrared Detection and Energy Harvesting Applications
In this letter we introduce a new type of infrared sensor, based on
thermocouple nanoantennas, which enables the energy detection and gathering in
the mid-infrared region. The proposed detector combines the Seebeck effect, as
a transduction mechanism, with the functionalities of the optical antennas for
optical sensing. By using finite-element numerical simulations we evaluate the
performance and optical-to-electrical conversion efficiency of the proposed
device, unveiling its potential for optical sensing and energy harvesting
applications.Comment: 4 pages, 3 figures, Invited paper at EUCAP 201
Silicon Nitride Waveguides for Plasmon Optical Trapping and Sensing Applications
We demonstrate a silicon nitride trench waveguide deposited with bowtie
antennas for plasmonic enhanced optical trapping. The sub-micron silicon
nitride trench waveguides were fabricated with conventional optical lithography
in a low cost manner. The waveguides embrace not only low propagation loss and
high nonlinearity, but also the inborn merits of combining micro-fluidic
channel and waveguide together. Analyte contained in the trapezoidal trench
channel can interact with the evanescent field from the waveguide beneath. The
evanescent field can be further enhanced by plasmonic nanostructures. With the
help of gold nano bowtie antennas, the studied waveguide shows outstanding
trapping capability on 10 nm polystyrene nanoparticles. We show that the bowtie
antennas can lead to 60-fold enhancement of electric field in the antenna gap.
The optical trapping force on a nanoparticle is boosted by three orders of
magnitude. A strong tendency shows the nanoparticle is likely to move to the
high field strength region, exhibiting the trapping capability of the antenna.
Gradient force in vertical direction is calculation by using a point-like
dipole assumption, and the analytical solution matches the full-wave simulation
well. The investigation indicates that nanostructure patterned silicon nitride
trench waveguide is suitable for optical trapping and nanoparticle sensing
applications
Optical Yagi-Uda nanoantennas
Conventional antennas, which are widely employed to transmit radio and TV
signals, can be used at optical frequencies as long as they are shrunk to
nanometer-size dimensions. Optical nanoantennas made of metallic or
high-permittivity dielectric nanoparticles allow for enhancing and manipulating
light on the scale much smaller than wavelength of light. Based on this
ability, optical nanoantennas offer unique opportunities regarding key
applications such as optical communications, photovoltaics, non-classical light
emission, and sensing. From a multitude of suggested nanoantenna concepts the
Yagi-Uda nanoantenna, an optical analogue of the well-established
radio-frequency Yagi-Uda antenna, stands out by its efficient unidirectional
light emission and enhancement. Following a brief introduction to the emerging
field of optical nanoantennas, here we review recent theoretical and
experimental activities on optical Yagi-Uda nanoantennas, including their
design, fabrication, and applications. We also discuss several extensions of
the conventional Yagi-Uda antenna design for broadband and tunable operation,
for applications in nanophotonic circuits and photovoltaic devices
Detection of deep-subwavelength dielectric layers at terahertz frequencies using semiconductor plasmonic resonators
Plasmonic bowtie antennas made of doped silicon can operate as plasmonic
resonators at terahertz (THz) frequencies and provide large field enhancement
close to their gap. We demonstrate both experimentally and theoretically that
the field confinement close to the surface of the antenna enables the detection
of ultrathin (100 nm) inorganic films, about 3750 times thinner than the free
space wavelength. Based on model calculations, we conclude that the detection
sensitivity and its variation with the thickness of the deposited layer are
related to both the decay of the local THz field profile around the antenna and
the local field enhancement in the gap of the bowtie antenna. This large field
enhancement has the potential to improve the detection limits of plasmon-based
biological and chemical sensors
Mid-Infrared Plasmonic Platform Based on n-Doped Ge-on-Si: Molecular Sensing with Germanium Nano-Antennas on Si
CMOS-compatible, heavily-doped semiconductor
films are very promising for applications in mid-infrared
plasmonic devices because the real part of their dielectric
function is negative and broadly tunable in this wavelength
range. In this work we investigate n-type doped germanium
epilayers grown on Si substrates. We design and realize Ge nanoantennas
on Si substrates demonstrating the presence of localized
plasmon resonances, and exploit them for molecular sensing in
the mid-infrared
Plasmonic nanoantennas as integrated coherent perfect absorbers on SOI waveguides for modulators and all-optical switches
The performance of plasmonic nanoantenna structures on top of SOI wire
waveguides as coherent perfect absorbers for modulators and all-optical
switches is explored. The absorption, scattering, reflection and transmission
spectra of gold and aluminum nanoantenna-loaded waveguides were calculated by
means of 3D finite-difference time-domain simulations for single waves
propagating along the waveguide, as well as for standing wave scenarios
composed from two counterpropagating waves. The investigated configurations
showed losses of roughly 1% and extinction ratios greater than 25 dB for
modulator and switching applications, as well as plasmon effects such as strong
field enhancement and localization in the nanoantenna region. The proposed
plasmonic coherent perfect absorbers can be utilized for ultracompact
all-optical switches in coherent networks as well as modulators and can find
applications in sensing or in increasing nonlinear effects.Comment: 10 pages, 6 figure
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