The Experts below are selected from a list of 26280 Experts worldwide ranked by ideXlab platform
Robert Magnusson - One of the best experts on this subject based on the ideXlab platform.
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quantification of neuropeptide y with picomolar sensitivity enabled by Guided Mode resonance biosensors
Sensors, 2019Co-Authors: Mohammad G Abdallah, Kyu Jin Lee, Joseph A Buchananvega, Brett R Wenner, Jeffery Allen, Monica S Allen, Susanne Gimlin, Debra Wawro Weidanz, Robert MagnussonAbstract:Assessing levels of neuropeptide Y (NPY) in the human body has many medical uses. Accordingly, we report the quantitative detection of NPY biomarkers applying Guided-Mode resonance (GMR) biosensor methodology. The label-free sensor operates in the near-infrared spectral region exhibiting distinctive resonance signatures. The interaction of NPY with bioselective molecules on the sensor surface causes spectral shifts that directly identify the binding event without additional processing. In the experiments described here, NPY antibodies are attached to the sensor surface to impart specificity during operation. For the low concentrations of NPY of interest, we apply a sandwich NPY assay in which the sensor-linked anti-NPY molecule binds with NPY that subsequently binds with anti-NPY to close the sandwich. The sandwich assay achieves a detection limit of ~0.1 pM NPY. The photonic sensor methodology applied here enables expeditious high-throughput data acquisition with high sensitivity and specificity. The entire bioreaction is recorded as a function of time, in contrast to label-based methods with single-point detection. The convenient methodology and results reported are significant, as the NPY detection range of 0.1-10 pM demonstrated is useful in important medical circumstances.
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fiber facet integrated Guided Mode resonance filters and sensors experimental realization
Optics Letters, 2018Co-Authors: Hafez Hemmati, Robert MagnussonAbstract:Guided-Mode resonant (GMR) thin films integrated on fiber tips are known to realize compact filters and sensors. However, limited progress in experimental realization has been reported to date. Here we provide a considerable advance in this technology, as we experimentally demonstrate efficient fiber-facet mounted device prototypes. To retain a large aperture for convenient coupling, we design and fabricate silicon nitride-based resonators on the tip of a multiMode fiber. We account for light propagation along the multiMode fiber with exact numerical methods. This establishes the correct amplitude and phase distribution of the beam incident on the tip-mounted GMR element, thus enabling us to properly predict the resonance response. To fabricate the integrated GMR structures on the tips of fibers, we employ standard microfabrication processes, including holographic interference lithography and reactive-ion etching. The experimental results agree with simulation with an example device achieving high efficiency of ∼77% in transmission. To investigate fiber sensor operation, an etched silicon nitride fiber tip filter is surrounded with solutions of various refractive indices, yielding an approximate sensitivity of 200 nm/RIU.
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broadband Guided Mode resonant reflectors with quasi equilateral triangle grating profiles
Optics Express, 2017Co-Authors: Shanwen Zhang, Robert MagnussonAbstract:We present the design of broadband Guided-Mode resonant reflectors consisting of a grating layer with quasi-equilateral grating profiles and a homogeneous layer made of silicon on glass. Using the coordinate-transformation-based differential method of Chandezon (the C method) to determine the optimized base angles of the grating and thickness of the homogeneous layer, we arrive at example reflector designs for TM polarization. We quantify the effects of deviation of the parameters, simulate the inner magnetic field distribution at resonance wavelengths, and compute the tolerance in the incident angle of the optimized broadband reflector. For broadband structures with different thicknesses of the homogeneous layer, the base angles of the triangles are all close to 60°. The optimized reflector has reflectance of R0 > 99% across a 567 nm bandwidth in the 1432-1999 nm wavelength range with fractional bandwidth of Δλ/λcenter ≈33.3%. Base angles play a critical role in determining the reflection bandwidth and the quasi-equilateral triangle profile is found to be the optimal configuration. This Model can be used to design broadband Guided-Mode resonant reflectors operating in different spectral bands and guide the fabrication of these devices with diamond-tip based grating ruling engines.
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flat top narrowband filters enabled by Guided Mode resonance in two level waveguides
Optics Letters, 2017Co-Authors: Katsuaki Yamada, Junichi Inoue, Kenji Kintaka, Shogo Ura, Kyu Jin Lee, Robert MagnussonAbstract:Resonant nanogratings and periodic metasurfaces express diverse spectral and polarization properties on broadside illumination by incident light. Cooperative resonance interactions may yield shaped spectra for particular applications, in contrast to a multilayer dielectric mirror. Here, we provide Guided-Mode resonance filters with flat-top spectra suitable for wavelength division multiplexing systems. Applying a single one-dimensional grating layer sandwiched by two waveguides, we theoretically achieve high-efficiency flat-top spectra in the near-infrared region. This result is obtained by inducing simultaneous nearly degenerate resonant Modes. The resonance separation under this condition controls the width of the flat-top spectrum. This means we can implement spectral widths ranging from a sub-nanometer to several nanometers applying fundamentally the same device architecture.
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high reflectance with steep reflection phase spectrum by Guided Mode resonance
Applied Physics Express, 2016Co-Authors: Katsuaki Yamada, Junichi Inoue, Kenji Kintaka, Shogo Ura, Kyu Jin Lee, Kosuke Asai, Robert MagnussonAbstract:A Guided-Mode resonance mirror (GMRM) consisting of a subwavelength grating integrated in an optical waveguide on a highly reflective substrate was predicted to give interesting characteristics of high reflectance with a steep reflection-phase spectrum. This time, the characteristics were experimentally demonstrated for the first time. A GMRM of 1535 nm resonance wavelength was designed and fabricated for a vertically injected wave from the air with TE polarization. The reflectance was measured to be higher than −1 dB over the wavelength from 1520 to 1560 nm. The reflection phase varied by π for a wavelength change of 10 nm.
Chengsheng Huang - One of the best experts on this subject based on the ideXlab platform.
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flexible linear and angular displacement sensor based on a gradient Guided Mode resonance filter
IEEE Sensors Journal, 2018Co-Authors: Yenchieh Wang, Chengsheng HuangAbstract:This paper reports a method for micrometer-scale linear and angular displacement measurement based on a gradient grating period Guided-Mode resonance (GGP-GMR) filter. When the filter is mounted on a moving or rotating object, the displacement on the object can be observed through the changes in the resonant wavelength, which are detected by the GGP-GMR filter. In this paper, the GGP-GMR filter comprised grating periods from 250 to 550 nm with 2-nm increments. Each period comprised 100 repeated cycles, resulting in a total length of 6 mm. For linear displacement, we achieved an average sensitivity of 67 nm/mm for a detection range of 6 mm and a theoretical limit of detection of $3~\mu \text{m}$ . To demonstrate the measurement of angular displacement, the GGP-GMR filter was attached to a cylinder with a diameter of 8 cm. The experimental results revealed an average sensitivity of 51.7 nm/° for a range of 7° and an experimental limit of detection of 0.002°.
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a gradient grating period Guided Mode resonance spectrometer
IEEE Photonics Journal, 2018Co-Authors: Hsinyun Hsu, Yi Hsuan Lan, Chengsheng HuangAbstract:This paper reports a compact spectrometer based on a Guided-Mode resonance (GMR) filter mounted on a linear charge-coupled device (CCD). The GMR is specially designed to exhibit gradient grating periods (GPPs) laterally to ensure that the GMR functions as a linear-variable bandstop filter. Each period corresponds to a resonant wavelength such that this wavelength is reflected back at its corresponding resonant period and transmitted to all other periods. Consequently, when a resonant wavelength is incident on the GGP-GMR attached to a linear CCD, the CCD pixel underneath its resonant period receives the minimum intensity, and the other pixels receive higher intensities. In terms of the wavelength range of interest, by scanning a single wavelength at a time, a transmission efficiency matrix that contains the transmission efficiency of each wavelength at each pixel can be established. An unknown incident spectrum can be reconstructed using the established transmission efficiency matrix and the intensity measured using the CCD. In this study, a GGP-GMR spectrometer less than 3 mm long that can achieve a wavelength detection range of 200 nm was demonstrated to reconstruct various incident spectra, including a single wavelength of light with a resolution of 0.5 nm, a single wavelength of light with varying intensity levels, and dual incident light sources.
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integration of a Guided Mode resonance filter with microposts for in cell protein detection
Analyst, 2016Co-Authors: M A Tsai, Hsinyun Hsu, Ichin Lee, Chengsheng HuangAbstract:We present an integrated microfluidic system consisting of a label-free biosensor of a Guided-Mode resonance filter (GMRF) and a microfluidic channel with a micropost filter. The GMRF was fabricated through replica molding using an ultraviolet-curable polymer and a plastic substrate. An array of microposts (a diameter and height of 26.5 and 56 μm, respectively, and a spacing between 7.5 and 9.5 μm), fabricated on a silicon substrate through photolithography, was used as the filter. A double-sided tape was used to laminate the GMRF and a microfluidic chip such that the integrated device provides two functions: filtration of the cell debris and quantification of the in-cell protein concentration. By measuring the changes in the resonant wavelength from the GMRF, the detection of β-actin in an unprocessed lysed cell sample was demonstrated; the cell debris was separated using the micropost filter to prevent false measurement.
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linear variable filter based on a gradient grating period Guided Mode resonance filter
IEEE Photonics Technology Letters, 2016Co-Authors: Hsinan Lin, Chengsheng HuangAbstract:In this letter, we fabricated and characterized a linear variable filter based on a Guided-Mode resonance filter (GMRF) with gradient grating periods. The GMRF was first fabricated through nanoreplica molding on a plastic substrate, which was followed by the deposition of a thin TiO2 film. The grating periods of the GMRF vary from 250 to 550 nm with a 2-nm increment in each period consisting of 100 cycles. The results show that a 6-mm-long GMRF has a filtering range of 506–915 nm.
Shogo Ura - One of the best experts on this subject based on the ideXlab platform.
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wavelength division multiplexer based on cavity resonator integrated Guided Mode resonance filters for a compact multi wavelength light source
Optics Express, 2018Co-Authors: Junichi Inoue, Kenji Kintaka, Kenzo Nishio, Atsushi Tsuji, Shogo UraAbstract:Cavity-resonator-integrated Guided-Mode resonance filters (CRIGF) consisting of a grating coupler in a waveguide resonator formed by two distributed Bragg reflectors of different reflectances can act as a wavelength-selective reflector and an input waveguide coupler for an incident free-space wave. Integration of CRIGFs in a waveguide is proposed to give an array of external mirrors and a wavelength division multiplexer for constructing a compact multi-wavelength light source. Four CRIGFs of 10-μm-size aperture with a wavelength spacing of 15 nm were designed and fabricated. The reflectance of 62% and output efficiency of higher than 18% were theoretically predicted. Multiplexing of four wavelengths was confirmed experimentally.
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flat top narrowband filters enabled by Guided Mode resonance in two level waveguides
Optics Letters, 2017Co-Authors: Katsuaki Yamada, Junichi Inoue, Kenji Kintaka, Shogo Ura, Kyu Jin Lee, Robert MagnussonAbstract:Resonant nanogratings and periodic metasurfaces express diverse spectral and polarization properties on broadside illumination by incident light. Cooperative resonance interactions may yield shaped spectra for particular applications, in contrast to a multilayer dielectric mirror. Here, we provide Guided-Mode resonance filters with flat-top spectra suitable for wavelength division multiplexing systems. Applying a single one-dimensional grating layer sandwiched by two waveguides, we theoretically achieve high-efficiency flat-top spectra in the near-infrared region. This result is obtained by inducing simultaneous nearly degenerate resonant Modes. The resonance separation under this condition controls the width of the flat-top spectrum. This means we can implement spectral widths ranging from a sub-nanometer to several nanometers applying fundamentally the same device architecture.
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high reflectance with steep reflection phase spectrum by Guided Mode resonance
Applied Physics Express, 2016Co-Authors: Katsuaki Yamada, Junichi Inoue, Kenji Kintaka, Shogo Ura, Kyu Jin Lee, Kosuke Asai, Robert MagnussonAbstract:A Guided-Mode resonance mirror (GMRM) consisting of a subwavelength grating integrated in an optical waveguide on a highly reflective substrate was predicted to give interesting characteristics of high reflectance with a steep reflection-phase spectrum. This time, the characteristics were experimentally demonstrated for the first time. A GMRM of 1535 nm resonance wavelength was designed and fabricated for a vertically injected wave from the air with TE polarization. The reflectance was measured to be higher than −1 dB over the wavelength from 1520 to 1560 nm. The reflection phase varied by π for a wavelength change of 10 nm.
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cavity resonator integrated Guided Mode resonance band stop reflector
Optics Express, 2016Co-Authors: Shogo Ura, Junichi Inoue, Masahiro Nakata, Kenichi Yanagida, Kenji KintakaAbstract:A cavity-resonator-integrated Guided-Mode resonance filter (CRIGF) consists of a grating coupler inside a pair of distributed Bragg reflectors. A combination of a CRIGF with a high-reflection substrate can provide a new type of a band-stop reflector with a small aperture for a vertically incident wave from air. A narrow stopband was theoretically predicted and experimentally demonstrated. It was quantitatively shown that reflection spectra depended on optical-buffer-layer thickness. The reflector of 10-μm aperture was fabricated and characterized. The extinction ratio in reflectance was measured to be lower than –20 dB at a resonance wavelength. The bandwidth at –3 dB was 0.15 nm.
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design of Guided Mode resonance mirrors for short laser cavities
Journal of The Optical Society of America A-optics Image Science and Vision, 2015Co-Authors: Tomohiro Kondo, Shogo Ura, Robert MagnussonAbstract:A Guided-Mode resonance mirror (GMRM) consists of a waveguide grating integrated on an optical buffer layer on a high-reflection substrate. An incident free-space wave at the resonance wavelength is once coupled by the grating to a Guided Mode and coupled again by the same grating back to free space. The reflection characteristics of a GMRM are numerically calculated and theoretically analyzed. It is predicted that notch filtering or flat reflection spectra are obtained depending on the optical buffer layer thickness. Design of short cavities using a GMRM is discussed for potential application in surface-mount packaging of diode lasers onto a photonic circuit board.
Krishna C Balram - One of the best experts on this subject based on the ideXlab platform.
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high frequency Guided Mode resonances in mass loaded thin film gallium nitride surface acoustic wave devices
Applied Physics Letters, 2019Co-Authors: Stefano Valle, Martin J Cryan, Manikant Singh, Martin Kuball, Krishna C BalramAbstract:We demonstrate high-frequency (>3 GHz), high quality factor radio frequency (RF) resonators in unreleased thin film gallium nitride (GaN) on sapphire and silicon carbide substrates by exploiting acoustic Guided Mode (Lamb wave) resonances. The associated energy trapping, due to mass loading from gold electrodes, allows us to efficiently excite these resonances from a 50 Ω input. The higher phase velocity, combined with lower electrode damping, enables high quality factors with Moderate electrode pitch and provides a viable route towards high-frequency piezoelectric devices. The GaN platform, with its ability to guide and localize high-frequency sound on the surface of a chip with access to high-performance active devices, will serve as a key building block for monolithically integrated RF front-ends.
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high frequency Guided Mode resonances in mass loaded thin film gallium nitride surface acoustic wave devices
arXiv: Applied Physics, 2019Co-Authors: Stefano Valle, Martin J Cryan, Manikant Singh, Martin Kuball, Krishna C BalramAbstract:We demonstrate high-frequency (> 3 GHz), high quality factor radio frequency (RF) resonators in unreleased thin film gallium nitride (GaN) on sapphire and silicon carbide substrates by exploiting acoustic Guided Mode (Lamb wave) resonances. The associated energy trapping, due to mass loading from the gold electrodes, allows us to efficiently excite these resonances from a 50 $\Omega$ input. The higher phase velocity, combined with lower electrode damping, enables high quality factors with Moderate electrode pitch, and provides a viable route towards high-frequency piezoelectric devices. The GaN platform, with its ability to guide and localize high-frequency sound on the surface of a chip with access to high-performance active devices, will serve as a key building block for monolithically integrated RF front-ends.
Brian T Cunningham - One of the best experts on this subject based on the ideXlab platform.
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optimally designed narrowband Guided Mode resonance reflectance filters for mid infrared spectroscopy
Optics Express, 2011Co-Authors: Jui Nung Liu, Matthew V Schulmerich, Rohit Bhargava, Brian T CunninghamAbstract:An alternative to the well-established Fourier transform infrared (FT-IR) spectrometry, termed discrete frequency infrared (DFIR) spectrometry, has recently been proposed. This approach uses narrowband mid-infrared reflectance filters based on Guided-Mode resonance (GMR) in waveguide gratings, but filters designed and fabricated have not attained the spectral selectivity (≤ 32 cm(-1)) commonly employed for measurements of condensed matter using FT-IR spectroscopy. With the incorporation of dispersion and optical absorption of materials, we present here optimal design of double-layer surface-relief silicon nitride-based GMR filters in the mid-IR for various narrow bandwidths below 32 cm(-1). Both shift of the filter resonance wavelengths arising from the dispersion effect and reduction of peak reflection efficiency and electric field enhancement due to the absorption effect show that the optical characteristics of materials must be taken into consideration rigorously for accurate design of narrowband GMR filters. By incorporating considerations for background reflections, the optimally designed GMR filters can have bandwidth narrower than the designed filter by the antireflection equivalence method based on the same index modulation magnitude, without sacrificing low sideband reflections near resonance. The reported work will enable use of GMR filters-based instrumentation for common measurements of condensed matter, including tissues and polymer samples.
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compact wavelength detection system incorporating a Guided Mode resonance filter
Applied Physics Letters, 2007Co-Authors: Nikhil Ganesh, Alan Xiang, Neill B Beltran, Dennis W Dobbs, Brian T CunninghamAbstract:The authors demonstrate a compact system for the detection of the peak wavelength value emitted by a light source. The system is composed of only two components, a graded-wavelength Guided-Mode resonance filter placed before a charge-coupled device sensor array. The filter provides a spatially resolved transmission minimum, the position of which is controlled by the wavelength of the incoming light. The sensor array collects the spatially resolved transmitted intensity and the wavelength is determined by recording the position of the transmission minimum along its length. Using this technique, wavelength changes as small as 0.011nm can be detected.
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fabrication of a graded wavelength Guided Mode resonance filter photonic crystal
Applied Physics Letters, 2006Co-Authors: Dennis W Dobbs, Irena Gershkovich, Brian T CunninghamAbstract:The authors report on the fabrication and characterization of a Guided-Mode resonance filter whose spectral reflectance features vary in a linear fashion as a function of position on the filter. This device was fabricated using nanoreplica molding in conjunction with a linearly graded TiO2 thin film deposition. The magnitude of gradation of the thin film was approximately 85nm over a distance of 26mm, which resulted in the spectral location of the primary reflection feature of the filter to be nearly linearly graded spanning a range of 798–909nm across the 26mm surface.