High-Q Microresonators at Near-Infrared/Near Visible Wavelengths on a 3C-SiC-on-Insulator (SiCOI) Platform

2018 ◽  
Author(s):  
Tianren Fan ◽  
Ali A Eftekhar ◽  
Ali Adibi
Keyword(s):  
Near Infrared ◽  
High Q ◽  
Visible Wavelengths

scholarly journals Lidar measurement of snow depth: a review

2013 ◽  
Vol 59 (215) ◽  
pp. 467-479 ◽  
Author(s):  
Jeffrey S. Deems ◽  
Thomas H. Painter ◽  
David C. Finnegan
Keyword(s):  
Remote Sensing ◽  
Snow Depth ◽  
Near Infrared ◽  
Ground Surface ◽  
Lidar Measurement ◽  
Snow Hydrology ◽  
Sensing Technology ◽  
Transfer Error ◽  
Scale Range ◽  
Visible Wavelengths

AbstractLaser altimetry (lidar) is a remote-sensing technology that holds tremendous promise for mapping snow depth in snow hydrology and avalanche applications. Recently lidar has seen a dramatic widening of applications in the natural sciences, resulting in technological improvements and an increase in the availability of both airborne and ground-based sensors. Modern sensors allow mapping of vegetation heights and snow or ground surface elevations below forest canopies. Typical vertical accuracies for airborne datasets are decimeter-scale with order 1 m point spacings. Ground-based systems typically provide millimeter-scale range accuracy and sub-meter point spacing over 1 m to several kilometers. Many system parameters, such as scan angle, pulse rate and shot geometry relative to terrain gradients, require specification to achieve specific point coverage densities in forested and/or complex terrain. Additionally, snow has a significant volumetric scattering component, requiring different considerations for error estimation than for other Earth surface materials. We use published estimates of light penetration depth by wavelength to estimate radiative transfer error contributions. This paper presents a review of lidar mapping procedures and error sources, potential errors unique to snow surface remote sensing in the near-infrared and visible wavelengths, and recommendations for projects using lidar for snow-depth mapping.

Near-infrared laser emission from high-Q polymer cavities

2005 ◽  
Author(s):  
Takeyuki Kobayashi ◽  
Martin Djiango ◽  
Grace Jordan ◽  
Manuel Rüther ◽  
Werner J. Blau ◽  
...  
Keyword(s):  
Near Infrared ◽  
Laser Emission ◽  
Infrared Laser ◽  
High Q

scholarly journals The inner dust shell of Betelgeuse detected by polarimetric aperture-masking interferometry

2019 ◽  
Vol 628 ◽  
pp. A101 ◽  
Author(s):  
X. Haubois ◽  
B. Norris ◽  
P. G. Tuthill ◽  
C. Pinte ◽  
P. Kervella ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Near Infrared ◽  
Mie Scattering ◽  
Parametric Models ◽  
Formation Mechanisms ◽  
Dust Shell ◽  
Stellar Radius ◽  
Fundamental Parameters ◽  
Red Supergiants ◽  
Visible Wavelengths

Context. Theory surrounding the origin of the dust-laden winds from evolved stars remains mired in controversy. Characterizing the formation loci and the dust distribution within approximately the first stellar radius above the surface is crucial for understanding the physics that underlie the mass-loss phenomenon. Aims. By exploiting interferometric polarimetry, we derive the fundamental parameters that govern the dust structure at the wind base of a red supergiant. Methods. We present near-infrared aperture-masking observations of Betelgeuse in polarimetric mode obtained with the NACO/SAMPol instrument. We used both parametric models and radiative transfer simulations to predict polarimetric differential visibility data and compared them to SPHERE/ZIMPOL measurements. Results. Using a thin dust shell model, we report the discovery of a dust halo that is located at only 0.5 R⋆ above the photosphere (i.e. an inner radius of the dust halo of 1.5 R⋆). By fitting the data under the assumption of Mie scattering, we estimate the grain size and density for various dust species. By extrapolating to the visible wavelengths using radiative transfer simulations, we compare our model with SPHERE/ZIMPOL data and find that models based on dust mixtures that are dominated by forsterite are most favored. Such a close dusty atmosphere has profound implications for the dust formation mechanisms around red supergiants.

scholarly journals Surface-Enhanced Absorption Spectroscopy for Optical Fiber Sensing

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 34
Author(s):  
Silje S. Fuglerud ◽  
Karolina Milenko ◽  
Astrid Aksnes ◽  
Dag R. Hjelme
Keyword(s):  
Optical Fiber ◽  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Real Life ◽  
Fiber Optic Probe ◽  
Enhanced Absorption ◽  
Au Film ◽  
Sensing Applications ◽  
Surface Enhanced ◽  
Visible Wavelengths

Visible and near-infrared spectroscopy are widely used for sensing applications but suffer from poor signal-to-noise ratios for the detection of compounds with low concentrations. Enhancement by surface plasmon resonance is a popular technique that can be utilized to increase the signal of absorption spectroscopy due to the increased near-field created close to the plasmons. Despite interest in surface-enhanced infrared absorption spectroscopy (SEIRAS), the method is usually applied in lab setups rather than real-life sensing situations. This study aimed to achieve enhanced absorption from plasmons on a fiber-optic probe and thus move closer to applications of SEIRAS. A tapered coreless fiber coated with a 100 nm Au film supported signal enhancement at visible wavelengths. An increase in absorption was shown for two dyes spanning concentrations from 5 × 10−8 mol/L to 8 × 10−4 mol/L: Rhodamine 6G and Crystal Violet. In the presence of the Au film, the absorbance signal was 2–3 times higher than from an identically tapered uncoated fiber. The results confirm that the concept of SEIRAS can be implemented on an optical fiber probe, enabling enhanced signal detection in remote sensing applications.

scholarly journals Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

2011 ◽  
Vol 4 (3) ◽  
pp. 3097-3145
Author(s):  
S. A. McFarlane ◽  
K. L. Gaustad ◽  
E. J. Mlawer ◽  
C. N. Long ◽  
J. Delamere
Keyword(s):  
Great Plains ◽  
Spectral Resolution ◽  
Surface Albedo ◽  
Vegetation Index ◽  
Near Infrared ◽  
High Spectral Resolution ◽  
Surface Type ◽  
Southern Great Plains ◽  
Green Vegetation ◽  
Visible Wavelengths

Abstract. We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

scholarly journals Photometric Properties of Vesta

2012 ◽  
Vol 10 (H16) ◽  
pp. 179-179 ◽  
Author(s):  
Jian-Yang Li ◽  
L. Jorda ◽  
H. U. Keller ◽  
N. Mastrodemos ◽  
S. Mottola ◽  
...  
Keyword(s):  
Multiple Scattering ◽  
Phase Function ◽  
Near Infrared ◽  
Roughness Parameter ◽  
Single Scattering ◽  
Asymmetry Factor ◽  
Linear Effect ◽  
Visible Wavelengths ◽  
Phase Angles ◽  
Geometric Albedo

AbstractThe Dawn spacecraft orbited Asteroid (4) Vesta for a year, and returned disk-resolved images and spectra covering visible and near-infrared wavelengths at scales as high as 20 m/pix. The visible geometric albedo of Vesta is ~ 0.36. The disk-integrated phase function of Vesta in the visible wavelengths derived from Dawn approach data, previous ground-based observations, and Rosetta OSIRIS observations is consistent with an IAU H-G phase law with H=3.2 mag and G=0.28. Hapke's modeling yields a disk-averaged single-scattering albedo of 0.50, an asymmetry factor of -0.25, and a roughness parameter of ~20 deg at 700 nm wavelength. Vesta's surface displays the largest albedo variations observed so far on asteroids, ranging from ~0.10 to ~0.76 in geometric albedo in the visible wavelengths. The phase function of Vesta displays obvious systematic variations with respect to wavelength, with steeper slopes within the 1- and 2-micron pyroxene bands, consistent with previous ground-based observations and laboratory measurement of HED meteorites showing deeper bands at higher phase angles. The relatively high albedo of Vesta suggests significant contribution of multiple scattering. The non-linear effect of multiple scattering and the possible systematic variations of phase function with albedo across the surface of Vesta may invalidate the traditional algorithm of applying photometric correction on airless planetary surfaces.

scholarly journals The Use of Upconversion Nanoparticles in Prostate Cancer Photodynamic Therapy

Life ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 360
Author(s):  
Michał Osuchowski ◽  
Filip Osuchowski ◽  
Wojciech Latos ◽  
Aleksandra Kawczyk-Krupka
Keyword(s):  
Prostate Cancer ◽  
Photodynamic Therapy ◽  
Near Infrared ◽  
Diagnostic Methods ◽  
Infrared Light ◽  
Upconversion Nanoparticles ◽  
Tissue Penetration ◽  
Deep Tissue ◽  
Visible Wavelengths ◽  
Intense Research

Photodynamic Therapy (PDT) is a cancer treatment that uses light, a photosensitizer, and oxygen to destroy tumors. This article is a review of approaches to the treatment of prostate cancer applying upconversion nanoparticles (UCNPs). UCNPs have become a phenomenon that are rapidly gaining recognition in medicine. They have proven to be highly selective and specific and present a powerful tool in the diagnosis and treatment of prostate cancer. Prostate cancer is a huge health problem in Western countries. Its early detection can significantly improve patients’ prognosis, but currently used diagnostic methods leave much to be desired. Recently developed methodologies regarding UCNP research between the years 2021 and 2014 for prostate cancer PDT will also be discussed. Current limitations in PDT include tissue irradiation with visible wavelengths that have a short tissue penetration depth. PDT with the objectives to synthesize UCNPs composed of a lanthanide core with a coating of adsorbed dye that will generate fluorescence after excitation with near-infrared light to illuminate deep tissue is a subject of intense research in prostate cancer.

scholarly journals Ultra Narrow Dual-Band Perfect Absorber Based on a Dielectric−Dielectric−Metal Three-Layer Film Material

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1552
Author(s):  
Bin Liu ◽  
Pinghui Wu ◽  
Hongyang Zhu ◽  
Li Lv
Keyword(s):  
Plasmon Resonance ◽  
Near Infrared ◽  
Incident Angle ◽  
Structural Parameters ◽  
Dual Band ◽  
Refractive Index Sensor ◽  
Perfect Absorber ◽  
Film Material ◽  
High Q ◽  
Magnetic Polaritons

This paper proposes a perfect metamaterial absorber based on a dielectric−dielectric−metal structure, which realizes ultra-narrowband dual-band absorption in the near-infrared band. The maximum Q factor is 484. The physical mechanism that causes resonance is hybrid coupling between magnetic polaritons resonance and plasmon resonance. At the same time, the research results show that the intensity of magnetic polaritons resonance is much greater than the intensity of the plasmon resonance. By changing the structural parameters and the incident angle of the light source, it is proven that the absorber is tunable, and the working angle tolerance is 15°. In addition, the sensitivity and figure of merit when used as a refractive index sensor are also analyzed. This design provides a new idea for the design of high-Q optical devices, which can be applied to photon detection, spectral sensing, and other high-Q multispectral fields.

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