scholarly journals Surface-enhanced mid-infrared absorption spectroscopy using miniaturized-disc metasurface

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mitchell Semple ◽  
Ashwin K. Iyer
Keyword(s):  
Infrared Spectroscopy ◽  
Signal To Noise Ratio ◽  
Low Cost ◽  
Unit Cell ◽  
Mid Infrared ◽  
Wide Range ◽  
Surface Enhanced ◽  
Identification Measurements ◽  
Vibrational Bands ◽  
On Chip

AbstractSurface-enhanced infrared spectroscopy is an important technique for improving the signal-to-noise ratio of spectroscopic material identification measurements in the mid-infrared fingerprinting region. However, the lower bound of the fingerprinting region receives much less attention due to a scarcity of transparent materials, more expensive sources, and weaker plasmonic effects. In this paper, we present a miniaturized metasurface unit cell for surface-enhanced infrared spectroscopy of the 15-$$\upmu$$ μ m vibrational band of CO$$_{2}$$ 2 . The unit cell consists of a gold disc, patterned along the edge with fine gaps/wires to create a resonant metamaterial liner. In simulation, our plasmonic metamaterial-lined disc achieves greater than $$4\times$$ 4 × the average field intensity enhancement of a comparable dipole array and a miniaturized size of $$\lambda _0/5$$ λ 0 / 5 using complex, 100-nm features that are patterned using 100-kV electron-beam lithography. In a simple experiment, the metamaterial-lined disc metasurface shows a high tolerance to fabrication imperfections and enhances the absorption of CO$$_{2}$$ 2 at 15 $$\upmu$$ μ m. The resonant wavelength and reflection magnitude can be tuned over a wide range by adjusting the liner feature sizes and the metasurface array pitch to target other vibrational bands. This work is a step toward low-cost, more compact on-chip integrated gas sensors.

scholarly journals Fabrication and Compressive Behavior of a Micro-Lattice Composite by High Resolution DLP Stereolithography

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 785
Author(s):  
Chow Shing Shin ◽  
Yu Chia Chang
Keyword(s):  
High Resolution ◽  
Lattice Structure ◽  
Low Cost ◽  
Hierarchical Structures ◽  
Dip Coating ◽  
Unit Cell ◽  
Digital Light Processing ◽  
Unit Cell Size ◽  
Wide Range ◽  
And Performance

Lattice structures are superior to stochastic foams in mechanical properties and are finding increasing applications. Their properties can be tailored in a wide range through adjusting the design and dimensions of the unit cell, changing the constituent materials as well as forming into hierarchical structures. In order to achieve more levels of hierarchy, the dimensions of the fundamental lattice have to be small enough. Although lattice size of several microns can be fabricated using the two-photon polymerization technique, sophisticated and costly equipment is required. To balance cost and performance, a low-cost high resolution micro-stereolithographic system has been developed in this work based on a commercial digital light processing (DLP) projector. Unit cell lengths as small as 100 μm have been successfully fabricated. Decreasing the unit cell size from 150 to 100 μm increased the compressive stiffness by 26%. Different pretreatments to facilitate the electroless plating of nickel on the lattice structure have been attempted. A pretreatment of dip coating in a graphene suspension is the most successful and increased the strength and stiffness by 5.3 and 3.6 times, respectively. Even a very light and incomplete nickel plating in the interior has increase the structural stiffness and strength by more than twofold.

scholarly journals Precise water level measurements using low-cost GNSS antenna arrays

2021 ◽  
Author(s):  
David J. Purnell ◽  
Natalya Gomez ◽  
William Minarik ◽  
David Porter ◽  
Gregory Langston
Keyword(s):  
Antenna Arrays ◽  
Tide Gauge ◽  
Signal To Noise Ratio ◽  
Low Cost ◽  
Satellite System ◽  
Water Levels ◽  
Optimum Number ◽  
Tide Gauges ◽  
Single Antenna ◽  
Wide Range

Abstract. We have developed a ground-based Global Navigation Satellite System Reflectometry (GNSS-R) technique for monitoring water levels with a comparable precision to standard tide gauges (e.g., pressure transducers) but at a fraction of the cost and using commercial products that are straightforward to assemble. As opposed to using geodetic-standard antennas that have been used in previous GNSS-R literature, we use multiple co-located low-cost antennas to retrieve water levels via inverse modelling of Signal-to-Noise ratio data. The low-cost antennas are advantageous over geodetic-standard antennas because they are much less expensive (even when using multiple antennas in the same location) and they can be used for GNSS-R analysis over a greater range of satellite elevation angles. We validate our technique using arrays of four antennas at three test sites with variable tidal forcing and co-located operational tide gauges. The root mean square error between the GNSS-R and tide gauge measurements ranges from 0.7–1.2 cm when using all four antennas at each site. We find that using four antennas instead of a single antenna improves the precision by 30–50 % and preliminary analysis suggests that four appears to be the optimum number of co-located antennas. In order to obtain precise measurements, we find that it is important for the antennas to track GPS, GLONASS and Galileo satellites over a wide range of azimuth angles (at least 140 degrees) and elevation angles (at least 30 degrees).

scholarly journals Electro-Absorption Modulation in GeSn Alloys for Wide-Spectrum Mid-Infrared Applications

2021 ◽  
Author(s):  
Yun-Da Hsieh ◽  
Jun-Han Lin ◽  
Richard Soref ◽  
Greg Sun ◽  
Hung-Hsiang Cheng ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Wide Spectrum ◽  
Complementary Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Optical Modulation ◽  
Bandgap Energy ◽  
Optical Modulators ◽  
Mid Infrared ◽  
Wide Range ◽  
On Chip

Abstract Si-based electronic-photonic integrated circuits (EPICs), which are compatible with state-of-the-art complementary metal-oxide-semiconductor (CMOS) processes, offer promising opportunities for on-chip mid-infrared (MIR) photonic systems. However, the lack of efficient MIR optical modulators on Si hinders the utilization of MIR EPICs. Here, we clearly demonstrate the Franz-Keldysh (FK) effect in GeSn alloys and achieve on-Si MIR electro-absorption optical modulation using GeSn heterostructures. Our experimental and theoretical results verify that the direct bandgap energy of GeSn can be widely tuned by varying the Sn content, thereby realizing wavelength-tunable optical modulation in the MIR range with a figure-of-merit of Δα /α0 (FOM) greater than 1.5 and a broadband operating range greater than 140 nm. In contrast to conventional silicon-photonic modulators based on the plasma dispersion effect, our GeSn heterostructure demonstrates practical and effective FK MIR optical modulation on Si and helps unlock the potential of MIR EPICs for a wide range of applications.

Automatic Baseline Subtraction of Vibrational Spectra Using Minima Identification and Discrimination via Adaptive, Least-Squares Thresholding

2012 ◽  
Vol 66 (5) ◽  
pp. 519-529 ◽  
Author(s):  
Andrew T. Weakley ◽  
Peter R. Griffiths ◽  
D. Eric Aston
Keyword(s):  
Signal To Noise Ratio ◽  
Local Level ◽  
Confidence Region ◽  
Baseline Correction ◽  
Threshold Region ◽  
Model Free ◽  
Baseline Subtraction ◽  
Surface Enhanced ◽  
Vibrational Bands ◽  
Threshold Criteria

A method of automated baseline correction has been developed and applied to Raman spectra with a low signal-to-noise ratio and surface-enhanced infrared absorption (SEIRA) spectra with bipolar bands. Baseline correction is initiated by dividing the raw spectrum into equally spaced segments in which regional minima are located. Following identification, the minima are used to generate an intermediate second-derivative spectrum where points are assigned as baseline if they reside within a locally defined threshold region. The threshold region is similar to a confidence interval encountered in statistics. To restrain baseline and band point discrimination to the local level, the calculation of the confidence region employs only a predefined number of already-accepted baseline minima as part of the sample set. Statistically based threshold criteria allow the procedure to make an unbiased assessment of baseline points regardless of the behavior of vibrational bands. Furthermore, the threshold region is adaptive in that it is further modified to consider abrupt changes in baseline. The present procedure is model-free insofar as it makes no assumption about the precise nature of the perturbing baseline nor requires treatment of spectra prior to execution.

scholarly journals Lane Compression

2021 ◽  
Vol 20 (2) ◽  
pp. 1-26
Author(s):  
Yousun Ko ◽  
Alex Chadwick ◽  
Daniel Bates ◽  
Robert Mullins
Keyword(s):  
Machine Learning ◽  
Low Cost ◽  
Huffman Coding ◽  
Statistical Characteristics ◽  
Learning Networks ◽  
Compression Technique ◽  
Wide Range ◽  
Run Time ◽  
On Chip ◽  
Learning Data

This article presents Lane Compression, a lightweight lossless compression technique for machine learning that is based on a detailed study of the statistical properties of machine learning data. The proposed technique profiles machine learning data gathered ahead of run-time and partitions values bit-wise into different lanes with more distinctive statistical characteristics. Then the most appropriate compression technique is chosen for each lane out of a small number of low-cost compression techniques. Lane Compression’s compute and memory requirements are very low and yet it achieves a compression rate comparable to or better than Huffman coding. We evaluate and analyse Lane Compression on a wide range of machine learning networks for both inference and re-training. We also demonstrate the profiling prior to run-time and the ability to configure the hardware based on the profiling guarantee robust performance across different models and datasets. Hardware implementations are described and the scheme’s simplicity makes it suitable for compressing both on-chip and off-chip traffic.

scholarly journals Waveguide excitation and collection of surface-enhanced Raman scattering from a single plasmonic antenna

Nanophotonics ◽  
2018 ◽  
Vol 7 (7) ◽  
pp. 1299-1306 ◽  
Author(s):  
Frédéric Peyskens ◽  
Pieter Wuytens ◽  
Ali Raza ◽  
Pol Van Dorpe ◽  
Roel Baets
Keyword(s):  
Signal To Noise Ratio ◽  
Single Mode ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sers Spectrum ◽  
Plasmonic Enhancement ◽  
Detection Scheme ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
On Chip

AbstractThe integration of plasmonic antennas on single-mode silicon nitride waveguides offers great perspective for integrated surface-enhanced Raman spectroscopy (SERS). However, the few reported experimental demonstrations still require multiple plasmonic antennas to obtain a detectable SERS spectrum. Here, we show, for the first time, SERS signal detection by a single nanoplasmonic antenna integrated on a single-mode SiN waveguide. For this purpose, we investigated a backscattering detection scheme in combination with background noise reduction, which allowed an optimization of the signal-to-noise ratio (SNR) of this platform. Furthermore, a comparison with the free-space SERS spectrum of the same antenna shows that the conversion efficiency from pump power to total radiated Stokes power is twice as efficient in the case of waveguide excitation. As such, we explored several important aspects in the optimization of on-chip SERS sensors and experimentally demonstrated the power of exciting nanoplasmonic antennas using the evanescent field of a waveguide. This observation not only is useful for Raman sensing but also could be beneficial for any process involving plasmonic enhancement.

The development of “fab-chips” as low-cost, sensitive surface-enhanced Raman spectroscopy (SERS) substrates for analytical applications

The Analyst ◽  
2015 ◽  
Vol 140 (3) ◽  
pp. 779-785 ◽  
Author(s):  
Ashley M. Robinson ◽  
Lili Zhao ◽  
Marwa Y. Shah Alam ◽  
Paridhi Bhandari ◽  
Scott G. Harroun ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Silver Nanoparticles ◽  
Chemical Sensing ◽  
Low Cost ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sers Substrates ◽  
Sensing Applications ◽  
Wide Range ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Modification of metal-coated zari fabric chips with silver nanoparticles results in sensitive, affordable SERS substrates which are useful for a wide range of chemical sensing applications.

Novel Lightpipes for Infrared Spectroscopy

1992 ◽  
Vol 46 (7) ◽  
pp. 1194-1197 ◽  
Author(s):  
S. J. Saggese ◽  
J. A. Harrington ◽  
G. H. Sigel ◽  
R. Altkorn ◽  
R. Haidle
Keyword(s):  
Infrared Spectroscopy ◽  
High Temperature ◽  
Low Cost ◽  
Infrared Transmission ◽  
Transmission Characteristics ◽  
Temperature Dependent ◽  
Low Loss ◽  
Mid Infrared ◽  
Temperature Performance ◽  
Ft Ir

The fabrication and temperature-dependent mid-infrared transmission characteristics of gold-on-nickel, silver-on-nickel, silica, and sapphire hollow lightpipes are discussed. The metal tubes offer improved low-temperature transmission and more versatile fabrication methods than do conventional FT-IR lightpipes. The dielectric tubes offer extremely low loss in certain spectral regions, outstanding high-temperature performance, and, in some cases, sufficiently low cost to be considered disposable.

scholarly journals Viaxl: A Solution of a Low-Cost Real-Time Visual Accelerometer Based on Laser Speckle Optical Flow Detection

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7033
Author(s):  
Zhitian Li ◽  
Wuhao Yang ◽  
Xingyin Xiong ◽  
Zheng Wang ◽  
Xudong Zou
Keyword(s):  
Optical Flow ◽  
Real Time ◽  
Signal To Noise Ratio ◽  
Low Cost ◽  
Laser System ◽  
Laser Speckle ◽  
Vibration Monitoring ◽  
Acceleration Measurement ◽  
Wide Range ◽  
Flow Detection

Non-contact and non-destructive acceleration measurement is receiving considerable attention due to their low cost, flexibility, and simplicity of implementation, as well as their excellent performance in some emerging applications such as medical electronics applications, vibration monitoring, and some other special scenarios. In this paper, a visual accelerometer system based on laser speckle optical flow detection named Viaxl is proposed. Compared with the conventional non-contact acceleration measurement method based on a laser system, Viaxl has moderate and stable performance with the advantages of low cost and simplicity of implementation. Experiment results demonstrate that Viaxl, which consists of a commercial camera and a low-cost laser pointer, can achieve real-time, non-contact acceleration measurement, and confirm the basic system performance of Viaxl: a measurement nonlinearity better than 1.3%, up to 31 dB signal-to-noise ratio, and 1150 Hz theoretic bandwidth; this demonstrates the huge potential of Viaxl in a wide range of applications, and provides a new possible technical method for non-contact acceleration detection.

System-on-Chip Integration

2002 ◽  
Vol 12 (02) ◽  
pp. 325-332
Author(s):  
ROBERT R. DOERING
Keyword(s):  
Low Cost ◽  
System On Chip ◽  
Foreseeable Future ◽  
Digital Cmos ◽  
Chip Area ◽  
Traditional System ◽  
Time Performance ◽  
Wide Range ◽  
On Chip ◽  
Process Complexity

Numerous "signal-processing products" are now driving the semiconductor market for SOC solutions enabling real-time performance, low-cost, low-power, portability, etc. A primary limit on the types of electronic (or other) functions that will be integrated into future SOCs is cost of integration, which tends to grow non-linearly with process complexity and chip area. A near-continuum of System-on/in-X solutions is emerging between traditional System-on-Chip and System-on-Board. These approaches span the tradeoff between bandwidth and cost. For the foreseeable future, digital CMOS will continue to serve as a "host platform" for integrating a wide range of mechanical, optical, biological, and, perhaps, even "quantum" technologies.

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