Optical spectroscopy study of Ca3(Ru0.91Mn0.09)2O7 single crystal in high magnetic fields
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Results for “OPTICS”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Topological Engineering of Interfacial Optical Tamm States for Highly Sensitive Near-Singular-Phase Optical Detection
Here, we developed planar multilayered photonic-plasmonic structures, which support topologically protected optical states on the interface between metal and dielectric materials, known as optical Tamm states. Coupling of incident light to the Tamm states can result in perfect absorption within one of several narrow frequency bands, which is accompanied by a singular behavior of the phase of electromagnetic field. In the case of near-perfect absorptance, very fast local variation of the phase can still be engineered. In this research, we theoretically and experimentally demonstrate how these drastic phase changes can improve sensitivity of optical sensors. A planar Tamm absorber was fabricated and used to demonstrate remote near-singular-phase temperature sensing with an over an order of magnitude improvement in sensor sensitivity and over two orders of magnitude improvement in the figure of merit over the standard approach of measuring shifts of resonant features in the reflectance spectra of the same absorber. Our experimentally demonstrated phase-to-amplitude detection sensitivity improvement nearly doubles that of state-of-the-art nano-patterned plasmonic singular-phase detectors, with further improvements possible via more precise fabrication. Tamm perfect absorbers form the basis for robust planar sensing platforms with tunable spectral characteristics, which do not rely on low-throughput nano-patterning techniques.
42 ENGINEERING↗
A technique for measuring the sea water optical parameters with a dedicated laser beam and a multi-PMT optical module
The KM3NeT research infrastructure will be a deep sea multidisciplinary observatory in the Mediterranean Sea housing a neutrino telescope. Accurate knowledge of the optical properties of the sea water is important for the performance evaluation of the telescope. In this work we describe a technique for the evaluation of the parameters describing the scattering characteristics of the sea water using one multi-PMT optical module that detects scattered optical photons which are emitted from a laser. Our results show that we are able to determine these parameters with satisfying precision and are able to resolve the scattering length values with less than half a meter accuracy.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Sequential x-ray diffraction topography at 1-BM x-ray optics testing beamline at the advanced photon source
We report progress on implementation and commissioning of sequential X-ray diffraction topography at 1-BM Optics Testing Beamline of the Advanced Photon Source to accommodate growing needs of strain characterization in diffractive crystal optics and other semiconductor single crystals. The setup enables evaluation of strain in single crystals in the nearly-nondispersive double-crystal geometry. Si asymmetric collimator crystals of different crystallographic orientations were designed, fabricated and characterized using in-house capabilities. Imaging the exit beam using digital area detectors permits rapid sequential acquisition of X-ray topographs at different angular positions on the rocking curve of a crystal under investigation. Results on sensitivity and spatial resolution are reported based on experiments with high-quality Si and diamond crystals. The new setup complements laboratory-based X-ray topography capabilities of the Optics group at the Advanced Photon Source.
43 PARTICLE ACCELERATORS↗
Deep-learning-aided extraction of optical constants in scanning near-field optical microscopy
Scanning near-field optical microscopy is one of the most effective techniques for spectroscopy of nanoscale systems. However, inferring optical constants from the measured near-field signal can be challenging because of a complicated and highly nonlinear interaction between the scanned probe and the sample. Conventional fitting methods applied to this problem often suffer from the lack of convergence or require human intervention. Here, we develop an alternative approach where the optical parameter extraction is automated by a deep learning network. The network provides an initial estimate that is subsequently refined by a traditional fitting algorithm. In conclusion, we show that this method demonstrates superior accuracy, stability against noise, and computational speed when applied to simulated near-field spectra.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
A cryogenic white light absorption spectroscopy setup with in situ gamma irradiation and thermo-optical annealing for optical fiber radiation-induced attenuation characterization
Silica optical fiber sensors offer a fast, distributed measurement solution in various cryogenic and radiation environments, such as magnets for fusion power. Under these conditions, light-absorbing point defects limit lifetime via radiation-induced attenuation (RIA). To support RIA kinetics prediction, we present an in situ, broadband absorption spectroscopy setup combining gamma irradiation with liquid nitrogen cooling. The apparatus enables continuous monitoring of narrowband RIA levels and the use of secondary optical annealing light sources, alongside broadband spectrum measurements to characterize RIA defects through spectrum decomposition. Initial results confirm the inevitable photobleaching effect of the probe light source, which must be accounted for. In addition, we report RIA kinetics during cycles of gamma irradiation at 77 K and isochronal thermal annealing steps from liquid nitrogen to room temperature, showcasing the setup’s ability to replicate real fiber operation scenarios. These instruments form an ideal platform to further study the kinetics of RIA coupled with thermal and optical annealing.
Absorption spectroscopy↗
Effects of haemodilution on the optical properties of blood during coagulation studied by optical coherence tomography
We report an investigation of the effects of blood dilution with hypertonic (7.5 %) and normal (0.9 %) saline on its optical properties during coagulation in vitro using optical coherence tomography. The light penetration depth and attenuation coefficient are obtained from the dependences of reflectance on the depth. Normal whole blood has served as the control group. The average coagulation time is equal to 420±16,418±16 and 358±14 s with blood volume replacement of 2 %, 11 %, and 20 % by 0.9 % normal saline, respectively. With 2 %, 11% and 20% blood volume replacement with 7.5 % hypertonic saline, the average coagulation time is 422±17,1160±45 and 1730±69 s, respectively. For normal whole blood, the average coagulation time amounts to 425±19 s. it is shown that dilution with normal saline has a procoagulant effect when it replaces 20 % of blood volume, and hypertonic saline has an anticoagulant effect if it replaces 11 % or more of blood volume. It is concluded that optical coherence tomography is a potential technique to quantify and monitor the liquid – gel transition during the coagulation process of blood diluted by normal and hypertonic saline. (biophotonics)
60 APPLIED LIFE SCIENCES↗
Laser optical frequency combs and their applications in optical fibre communication systems and astrophysics
This paper examines the generation and applications of laser optical frequency combs (LOFCs). The unique properties of LOFCs are widely used in spectroscopy and metrology, in particular for making ultra-accurate optical clocks. The use of LOFCs contributes to advances in optical fibre communication systems and studies pertaining to fundamental problems of astrophysics, such as the search for and investigation of exoplanets and verification of the hypothesis that physical constants vary with time. (invited paper)
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Acousto-optic modulators for fibre-optic lines
The specific features of efficient matching of acousto-optic devices with single-mode fibres for the cases of isotropic and anisotropic diffraction are considered. The acousto-optic interaction geometry, optimal for modulating an arbitrarily polarised light beam with a possibility of tuning its frequency shift in the range up to ∼10 MHz, is chosen. Acousto-optic modulators/frequency shifters based on paratellurite (TeO{sub 2}), pigtailed with polarisation-maintaining and non-polarisation-maintaining fibres, have been developed for wavelengths of 1064 and 1550 nm, and their main technical parameters are investigated. (paper)
36 MATERIALS SCIENCE↗
A Free Spectroscopic Databank of Optical Constants for Use in Optics Education and Modeling: complex refractive index data n and k from 1.0 to 25 um
The reflectance spectra of solid and liquids can be complicated since they depend not only on absorption, but also on the refraction, reflection, and scattering of light, all of which are wavelength dependent. The physical form and morphological effects associated with solid and liquid samples are thus known to affect their reflectance spectra in a non-linear fashion, particularly in the infrared. Measuring the optical constants n(?) and k(?) represents an alternative approach, allowing one to model these many effects and thus requiring fewer laboratory measurements. In this paper an overview is presented of the protocols used to measure the n/k optical constants, particularly for liquids. For the liquids, a multiple path length measurements approach is employed, and in this paper we demonstrate the method to determine the complex optical constants n(?) and k(?) of squalene. The resultant calculated spectra of 1 µm and 100 µm thick layers of squalene on an aluminum substrate as derived from the experimental n(?) and k(?) values are shown to demonstrate such effects. The public availability of the n(?)/k(?) data as well as solids hemispherical reflectance data are also discussed.
optical constants, refractive index, solids, Liqui↗
Polarization-Controlled Topological Charge Inversion of Optical Vortices in Multielliptical Optical Fibers
Analytical expressions for higher-order modes with azimuthal number |ℓ|≥ 2and their propagation constants for multielliptical optical fibers exhibiting a torsional mechanical stress are obtained in the vicinity of the resonance twist-pitch values. It is demonstrated that the resonance modes represent a superposition of two optical vortices with identical circular polarization and opposite signs of the topological charge. The effect of topological-charge inversion of the output optical vortex controlled by a change of sign of the circular polarization of the input beam is predicted. This effect paves the way to creating a logical CNOT element based on multielliptical fibers.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Acousto-Optic Commutation of Fiber-Optic Channels
An acousto-optic commutator of fiber-optic channels based on a ТеО{sub 2} two-coordinate deflector has been proposed and realized. The commutator yields switching of optical radiation from a single output waveguide into a two-dimensional input matrix of waveguides, or vice versa, switching from any matrix waveguide into a single output one. The main interrelated parameters have been obtained. It has been established that the commutator has a short response time of 2–10 μs, yields up to several hundreds of switching channels, low insertion losses of 2–5 dB, and a considerable inter-channel isolation from –35 to –60 dB. Experiments were performed for the output matrix containing 19 waveguides. The channel multiplexing operating mode of this commutator has been demonstrated, which is simultaneous transmission of a signal from the output waveguide into a given number of waveguides of the input matrix.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Ultralow-threshold thin-film lithium niobate optical parametric oscillator
Materials with strong second-order ( χ <#comment/> ( 2 ) ) optical nonlinearity, especially lithium niobate, play a critical role in building optical parametric oscillators (OPOs). However, chip-scale integration of low-loss χ <#comment/> ( 2 ) materials remains challenging and limits the threshold power of on-chip χ <#comment/> ( 2 ) OPO. Here we report an on-chip lithium niobate optical parametric oscillator at the telecom wavelengths using a quasi-phase-matched, high-quality microring resonator, whose threshold power ( ∼ <#comment/> 30 µ <#comment/> W ) is 400 times lower than that in previous χ <#comment/> ( 2 ) integrated photonics platforms. An on-chip power conversion efficiency of 11% is obtained from pump to signal and idler fields at a pump power of 93 µW. The OPO wavelength tuning is achieved by varying the pump frequency and chip temperature. With the lowest power threshold among all on-chip OPOs demonstrated so far, as well as advantages including high conversion efficiency, flexibility in quasi-phase-matching, and device scalability, the thin-film lithium niobate OPO opens new opportunities for chip-based tunable classical and quantum light sources and provides a potential platform for realizing photonic neural networks.
Lu, Juanjuan (ORCID:0000000319389119)↗
Active Irradiation Testing of Temperature Sensing Capability of Clad Sapphire Optical Fibers with Type 2 Bragg Gratings using Optical Backscatter Reflectometry
This work investigated the temperature-sensing capabilities of Type II fiber Bragg gratings (FBGs) inscribed in sapphire optical fiber in the Ohio State University Research Reactor (OSURR). A Luna Innovations 4600 optical backscatter reflectometer (OBR) was used to interrogate FBGs in three sapphire optical fibers with an internal cladding that was developed by Ohio State. The sapphire fibers were fusion-spliced to silica lead fibers. In addition to the sapphire fibers, two silica fibers with the same Type II FBGs were included in the experiment as a reference. The fiber-based sensors were irradiated in the Central Irradiation Facility (CIF) of the OSURR for a total of 40 hours over 5 days at a reactor power of 450 kW, resulting in a total neutron fluence of approximately 2.5 × 10 18 n/cm 2 and a gamma dose of approximately 3.48 Grad. Two K-type thermocouples were included within the rig: one at the core centerline and the other 12 inches above the top of the core. The temperature was not actively controlled, but the thermocouples were used to provide a reference to which the fiber-based temperature measurements could be compared.
36 MATERIALS SCIENCE↗
Commercialization of a Non-Intrusive Optical (NIO) Technology to Measure Heliostat Optical Errors in Utility-Scale Concentrating Solar Power Plants: Final TCF Report
The drone-based Non-Intrusive Optical (NIO) Technology has been developed at NREL to allow for efficient and automated optical characterization of heliostats in Concentrating Solar Power (CSP) plants. For this project, the technology will be developed into a commercial tool package, including software and user-interface (UI), operations manual, and training and support services. The project team will partner with Tietronix to perform market assessment and stakeholder engagement, develop the tool package and business model, and perform data collection and analysis to demonstrate and refine the capabilities for use at a commercial plant. The team will collaborate with a commercial plant to conduct the data collection operations and provide optical error deliverables. The goal of the project is to advance the commercialization of the technology to a stage where a beta version can be demonstrated at additional commercial plants and developed into a licensable product.
14 SOLAR ENERGY↗
Design of the Optical Communication Demonstrator Instrument Optical System
This paper describes the optical system for the Optical Communication Demonstrator (OCD) instrument. With an aperture of only 4 inches, the OCD instrument is designed to demonstrate the capability of communicating from space to a ground station with a small instrument using optical wavelengths.
Optical↗
A Method for Measuring Optical Distortion in Curved Optical Surfaces using Moiré Interferometry
In FY2020, KSC’s Applied Physics Lab created a computer based image processing system to allow inspection of the new visors being developed for the Artemis Program. This system was based on an ASTM standard where the distortion of an image is used to determine the optical aberrations in a visor, but this approach is restricted to small fields-of-view (small areas of the visor) and is limited in its ability to reliably detect and measure distortion. From our experience with flat surface inspection, we know that other optical techniques can offer higher sensitivity and accuracy. [1] This memorandum describes a method to model and measure the distortion in curved optical surfaces using moir´e interferometry. We were able to apply this process to examine samples of the xEMU Artemis astronaut helmets. Design details are provided along with examples to illustrate performance.
Optical Distortion↗
Optical Characteristics of Radiated Multifunctional Optical Materials
The performance of optical and electronic materials, and devices are affected significantly in space due to exposure from high energy radiations. We have been investigating the effect of -ray radiations on multifunctional binary and ternary selenide and halide crystals. These materials have shown excellent performance for the wavelength conversion in MWIR and LWIR regions, acousto-optics, and great potential for radiation detection. Crystals with high Z materials such as thallium, mercury and lead based compounds have great potential for the development of a variety of devices and components suitable for space applications. We will report on the characteristics of several halides including mercurous halides (Hg2X2, X= Cl, Br, I), Thallium mercury iodide (Tl4HgI4) and thallium arsenic selenide and thallium gallium selenide, and ternary selenides. These crystals, synthesized with high purity source materials, will be evaluated by studying optical characteristics and measuring resistivity after exposure to a 137Cs -ray source.
Radiation↗