Plasmonic sensing using surface plasmon resonances remains an area with unclear detection limits. The introduction of metallic nanostructures as nanoantennas can improve plasmonic sensing through localized surface plasmon resonances (LSPR), complex lattice effects, and simultaneous propagating plasmons. The combination of plasmonic effects through near or far-field coupling lead to more complex phenomena called plasmonic hybridization. Multivariate analysis methods significantly improve the sensing performance in terms of figures of merit by exploiting multiple features of the resonance curves. Likewise, multivariate design approaches provide optimized plasmonic substrates through electromagnetic simulations when the same curve features are used as in multivariate data analysis to achieve optimized performance metrics. Here, we demonstrate with one-dimensional gold nanogratings that multivariate design concepts lead to optimized performance in plasmonic sensing, which is also confirmed experimentally.
The silicon photonics industry is projected to be a multibillion dollar industry driven by the growth of data centers. In this work, we present an interactive online tool for silicon photonics. Silicon Photonics Cloud (SiCCloud.org) is an easy to use instructional tool for optical properties of silicon and related materials, waveguide design and modal simulations as well as information capacity of silicon channels.
The transmittance, reflectance and absorption of silver nanowires metamaterial embedded into a semiconductor matrix with optical gain are numerically investigated. Metamaterials may suffer from appreciable dissipative losses which are inherent for all plasmonic structures. The losses can significantly be reduced by introducing optical gain in the dielectric matrix by placing atomic or molecular impurities which are pumped by an external light source to create a population inversion. We numerically analyzed the optical properties when the semiconductor host material represents a gain medium. We calculate the transmittance, reflectance and absorption at normal incidence in the visible and near infrared ranges. We observed a peculiar behavior of their optical coefficients that can be explained by observing the field redistribution on the metamaterial.
Although organic solar cells show intriguing features such as low-cost, mechanical flexibility and light weight, their efficiency is still low compared to their inorganic counterparts. One way of improving their efficiency is by the use of light-trapping mechanisms from nano- or microstructures, which makes it possible to improve the light absorption and charge extraction in the device’s active layer. Here, periodically arranged colloidal gold nanoparticles are demonstrated experimentally and theoretically to improve light absorption and thus enhance the efficiency of organic solar cells. Surface-ordered gold nanoparticle arrangements are integrated at the bottom electrode of organic solar cells. The resulting optical interference and absorption effects are numerically investigated in bulk hetero-junction solar cells based on the Finite-Difference Time-Domain (FDTD) and Transfer Matrix Method (TMM) and as a function of size and periodicity of the plasmonic arrangements. In addition, light absorption enhancement in the organic active layer is investigated experimentally following integration of the nanoparticle arrangements. The latter are fabricated using a lithography-free stamping technique, creating a centimeter scaled area with nanoparticles having a defined inter-particle spacing. Our study reveals the light harvesting ability of template-assisted nanoparticle assemblies in organic solar cells. As the approach is easily scalable, it is an efficient and transferable method for large-scale, low cost device fabrication.
Recent research on hybrid plasmonic systems has shown the existence of a loss channel for energy transfer between
organic materials and plasmonic/metallic structured substrates. This work focuses on the exciton-plasmon coupling
between para-Hexaphenylene (p-6P) organic nanofibers (ONFs) and surface plasmon polaritons
(SPPs) in organic/dielectric/metal systems. We have transferred the organic p-6P nanofibers onto a thin silver film
covered with a dielectric (silicon dioxide) spacer layer with varying thicknesses. Coupling is investigated by two-photon
fluorescence-lifetime imaging microscopy (FLIM) and leakage radiation spectroscopy (LRS). Two-photon excitation
allows us to excite the ONFs with near-infrared light and simultaneously avoids direct SPP excitation on the metal layer.
We observe a strong dependence of fluorescence lifetime on the type of underlying substrate and on the morphology of
the fibers. The experimental findings are complemented via finite-difference time-domain (FDTD) modeling. The
presented results lead to a better understanding and control of hybrid-mode systems, which are crucial elements in future
low-loss energy transfer devices.
A promising method for improving light-absorption in thin-film devices is demonstrated via electrode structuring
using Anodic Alumina Oxide (AAO) templates. We present nano-scale concave Al structures of controlled dimensions,
formed after anodic oxidation of evaporated high purity aluminum (Al) films and alumina etching. We investigate both
experimentally and theoretically the field-enhancement supported by these concave nanostructures as a function of their
dimensions. For the experimental investigations, a thin layer of organic polymer coating allows the application of a nondestructive
laser ablation technique that reveals field-enhancement at the ridges of the Al nanostructures. The
experimental results are complemented by finite-difference time-domain (FDTD) simulations, to support and explain the
outcome of the laser ablation experiments. Our method is easily up-scalable and lithography-free and allows one to
generate nanostructured electrodes that potentially support field-enhancement in organic thin-film devices, e.g., for the
use in future energy harvesting applications.
The angular light scattering profile of microscopic particles significantly depends on their morphological parameters, such as size and shape. This dependency is widely used in state-of-the-art flow cytometry methods for particle classification. We recently introduced the spectrally encoded angular light scattering (SEALS) method, with potential application in scanning flow cytometry (SFC). We show that a one-to-one wavelength-to-angle mapping enables the measurement of the angular dependence of scattered light from microscopic particles over a wide dynamic range. Improvement in dynamic range is obtained by equalizing the angular scattering dependence via spectral equalization. The resulting continuous angular spectrum is obtained without mechanical scanning, enabling single-shot measurement. Using this information, particle morphology can be determined with improved accuracy. We derive and experimentally verify an analytic wavelength-to-angle mapping model, facilitating rapid data processing. As a proof of concept, we demonstrate the method’s capability of distinguishing differently sized polystyrene beads. The combination of SEALS with time-stretch dispersive Fourier transform (TS-DFT) offers real-time and high-throughput (high frame rate) measurements and renders the method suitable for integration in standard flow cytometers: By transforming the spectrum into time and slowing the time scale, using group velocity dispersion (GVD), single-shot spectra can be obtained at high throughput, using a photodiode and a real-time digitizer. The amount of group velocity dispersion is chosen to time-stretch the optical pulses, that is, to slow them down, such that they do not overlap and may be digitized in real-time.
Apertures are basic elements which can be found in many optical systems. Since optical systems are continuously being miniaturized and integrated, there is a need for small and inexpensive apertures to control beam shape and light intensity. Current aperture concepts for the micrometer regime rely on moving MEMS lamella or controlling fluids by capillary or electrostatic forces. We demonstrate an aperture concept for single-wavelength operation based on thermal tuning of a segmented thin film resonator. Thermal tuning changes the optical thickness of the elastomer cavity. This allows for adjusting the intensity to any level between constructive and destructive interference in a specific aperture segment. In order to demonstrate aperture operation we simulate thermal, mechanical and optical properties using finite element method and transfer-matrix method. We confirm our simulation results by experimental beam shape measurements and spatially-resolved spectral transmission and light intensity measurements.
Guided mode resonance biosensors are of emerging interest as they allow integration on chip with fabrication on mass scale. The guided mode resonances (GMRs), observed in the transmission or reflection spectrum, are sensitive to refractive index changes in the vicinity of the photonic crystal (PhC) surface. Standard measurement setups utilize a collecting lens, focusing the extracted light intensity onto a single-point photo detector. In order to achieve highly miniaturized devices, we consider the integration of planar emitting and detector structures, such as organic light emitting diodes (OLEDs) and organic photo detectors (OPDs), together with the PhC based biosensors, on a single chip. This approach, however, consequently leads to a broadband, multi-angular light excitation as well as to a broadband and multi-angular contribution to the OPD photon count. While GMR effects in PhC slabs with directional light sources have been widely studied, this lens-less scenario requires a deep understanding regarding the broadband and the angular influence of both incident and reflected or transmitted light. We performed finite-difference time-domain (FDTD) calculations for GMR effects in two-dimensional (2D) PhC slabs. We study the effects for broadband emission in the visible spectrum, together with an angular incident beam divergence of up to 80°. We verified the simulated results by performing angle-resolved spectral measurements with a light emitting diode (LED) in a macroscopic, lens-less setup. We further utilize this numerical setup to provide a deeper understanding of the modal behaviour of our proposed OLED and OPD-based integrated biosensor concept.
The current autostereoscopic projection system is accomplished by array projectors. It is easy to realize optically but
has a drawback with size. Another type is to place the shutter on the screen. It saves the volume but reduces the
efficiency depending on how many views are produced. The shutter in the lens aperture has the same efficiency
problem, too. To overcome these problems, a full HD autostereoscopic projector based on the lens aperture switching
type is proposed. It has RGB laser sources and can produce 16-views or even higher stereoscopic images.
This system removes the shutter in the lens aperture by the opti-mechanism itself. The specific light on the lens
aperture coming from the point on the DMD is reflected to different angles. The proper angle of light is generated in
the object side by the relay and folding system. The UHP lamps or the LED rays are difficult to constrain in a relative
small cone angle. For this reason, the laser is applied to the design. The very small etendue of the laser is good for
this architecture. The rays are combined by dichroic filter from RGB laser sources then forming and expanding to the
mirror. The mirror is synchronized with DMD by the DSP control system. The images of different views are
generated by DMD and specific position of the mirror. By the double lenticular screen, the lens aperture is imaged to
the observer’s viewing zone and the 3D scene is created.
Laser scanners are essential for scientific research, manufacturing, defense, and medical practice. Unfortunately, often times the speed of conventional laser scanners (e.g., galvanometric mirrors and acousto-optic deflectors) falls short for many applications, resulting in motion blur and failure to capture fast transient information. Here, we present a novel type of laser scanner that offers roughly three orders of magnitude higher scan rates than conventional methods. Our laser scanner, which we refer to as the hybrid dispersion laser scanner, performs inertia-free laser scanning by dispersing a train of broadband pulses both temporally and spatially. More specifically, each broadband pulse is temporally processed by time stretch dispersive Fourier transform and further dispersed into space by one or more diffractive elements such as prisms and gratings. As a proof-of-principle demonstration, we perform 1D line scans at a record high scan rate of 91 MHz and 2D raster scans and 3D volumetric scans at an unprecedented scan rate of 105 kHz. The method holds promise for a broad range of scientific, industrial, and biomedical applications. To show the utility of our method, we demonstrate imaging, nanometer-resolved surface vibrometry, and high-precision flow cytometry with real-time throughput that conventional laser scanners cannot offer due to their low scan rates.
Virtually imaged phased arrays (VIPA) offer high dispersion compared to conventional gratings and have been proposed as buildings blocks for several photonic devices, including wavelength multipliers, chromatic dispersion compensators, waveformgenerators and pulse shapers. We introduce an elastomer-based tunable VIPA, providing an additional degree of freedom for these devices. In particular, we investigate its capability to implement reconfigurable optical interconnects. In a wavelength demultiplexing setup it allows for both compensation of misalignment as well as reconfiguration of a source wavelength to a target channel. It consists of an elastomer layer sandwiched between two structured silver coatings on a glass substrate forming the resonator cavity. Using Joule heating of the top silver layer a thermal expansion and a thermo-optic effect of the elastomer cavity is induced allowing for tuning the effective optical resonator cavity. We report a tuning span of one free angular range by a temperature increase of less than 10K induced by a power change in the low mW regime. Both resonance quality and tunability of the device are investigated.
We describe a real-time image processor that has enabled a new automated flow through microscope to screen cells in
flow at 100,000 cells/s and a record false positive rate of one in a million. This unit is integrated with an ultrafast optical
imaging modality known as serial time-encoded amplified microscopy (STEAM) for blur-free imaging of particles in
high-speed flow. We show real-time image-based identification and screening of budding yeast cells and rare breast
cancer cells in blood. The system generates E-slides (an electronic version of glass slides) on which particles of interest
are digitally analyzed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.