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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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All sources NASA NTRS DOE OSTI

DOE OSTI2013

Latching micro optical switch

An optical switch reliably maintains its on or off state even when subjected to environments where the switch is bumped or otherwise moved. In addition, the optical switch maintains its on or off state indefinitely without requiring external power. External power is used only to transition the switch from one state to the other. The optical switch is configured with a fixed optical fiber and a movable optical fiber. The movable optical fiber is guided by various actuators in conjunction with a latching mechanism that configure the switch in one position that corresponds to the on state and in another position that corresponds to the off state.

42 ENGINEERING↗

DOE OSTI2014

Background-free balanced optical cross correlator

A balanced optical cross correlator includes an optical waveguide, a first photodiode including a first n-type semiconductor and a first p-type semiconductor positioned about the optical waveguide on a first side of the optical waveguide's point of symmetry, and a second photodiode including a second n-type semiconductor and a second p-type semiconductor positioned about the optical waveguide on a second side of the optical waveguide's point of symmetry. A balanced receiver including first and second inputs is configured to produce an output current or voltage that reflects a difference in currents or voltages, originating from the first and the second photodiodes of the balanced cross correlator and fed to the first input and to the second input of the balanced receiver.

43 PARTICLE ACCELERATORS↗

DOE OSTI2015

Method and system for processing optical materials for high power laser systems

A method of determining conditioning pulse parameters for an optical element includes directing a pump pulse to impinge on the optical element and directing a probe pulse to impinge on the optical element. The method also includes determining a first time associated with an onset of electronic excitation leading to formation of an absorbing region of the optical element and determining a second time associated with expansion of the absorbing region of the optical element. The method further includes defining a turn-off time for a conditioning pulse between the first time and the second time. According to embodiments of the present invention, pulse shaping of the conditioning pulse enables laser conditioning of optical elements to achieve improvements in their laser induced damage threshold.

42 ENGINEERING↗

DOE OSTI2015

Mach-zehnder based optical marker/comb generator for streak camera calibration

This disclosure is directed to a method and apparatus for generating marker and comb indicia in an optical environment using a Mach-Zehnder (M-Z) modulator. High speed recording devices are configured to record image or other data defining a high speed event. To calibrate and establish time reference, the markers or combs are indicia which serve as timing pulses (markers) or a constant-frequency train of optical pulses (comb) to be imaged on a streak camera for accurate time based calibration and time reference. The system includes a camera, an optic signal generator which provides an optic signal to an M-Z modulator and biasing and modulation signal generators configured to provide input to the M-Z modulator. An optical reference signal is provided to the M-Z modulator. The M-Z modulator modulates the reference signal to a higher frequency optical signal which is output through a fiber coupled link to the streak camera.

42 ENGINEERING↗

DOE OSTI2015

Diffractive optical elements for transformation of modes in lasers

Spatial mode conversion modules are described, with the capability of efficiently transforming a given optical beam profile, at one plane in space into another well-defined optical beam profile at a different plane in space, whose detailed spatial features and symmetry properties can, in general, differ significantly. The modules are comprised of passive, high-efficiency, low-loss diffractive optical elements, combined with Fourier transform optics. Design rules are described that employ phase retrieval techniques and associated algorithms to determine the necessary profiles of the diffractive optical components. System augmentations are described that utilize real-time adaptive optical techniques for enhanced performance as well as power scaling.

42 ENGINEERING↗

DOE OSTI2016

Thermally tuneable optical modulator adapted for differential signaling

An apparatus for optical modulation is provided. The apparatus includes a modulator structure and a heater structure. The modulator structure comprises a ring or disk optical resonator having a closed curvilinear periphery and a pair of oppositely doped semiconductor regions within and/or adjacent to the optical resonator and conformed to modify the optical length of the optical resonator upon application of a bias voltage. The heater structure comprises a relatively resistive annulus of semiconductor material enclosed between an inner disk and an outer annulus of relatively conductive semiconductor material. The inner disk and the outer annulus are adapted as contact regions for a heater activation current. The heater structure is situated within the periphery of the optical resonator such that in operation, at least a portion of the resonator is heated by radial conductive heat flow from the heater structure. The apparatus further includes a substantially annular isolation region of dielectric or relatively resistive semiconductor material interposed between the heater structure and the modulator structure. The isolation region is effective to electrically isolate the bias voltage from the heater activation current.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2013

Characterization of Polarizing Splitter Optics in Extreme Environments

Development of laser systems capable of surviving extreme conditions experienced in military applications requires mounts and components that are able to survive these conditions. The characterization of mounted and/or bonded optical assemblies in harsh environments is critical for the development of laser and optical systems for functionality in these extreme conditions. Customized mounts, bonding assemblies and packaging strategies are utilized to develop and field reliable and robust optical subassemblies. Thin film polarizers operating at 45o and polarizing beam splitter cubes were chosen for initial testing based on past experiences, advancements in optical coating and construction technologies and material properties. Shock, vibration, shear strength, tensile strength and temperature testing are performed on mounted polarizing beam splitter cubes and thin film polarizers from two manufacturers. Previous testing showed that polarizing beam splitter cubes constructed using epoxy would become damaged in the laser resonator. The cubes being tested in this report are constructed using epoxy- free direct optical contact bonding. Thin film polarizers operating at 45o are chosen opposed to Brewster’s angle thin film polarizers to reduce the size and simplify design and construction since an optical wedge is not required. The components and mounts are each environmentally tested beyond the manufacturers’ specifications for shock, vibration, and temperature. Component functionality is monitored during and after the environmental testing. Experimental results from the testing will be discussed as will the impact on future laser resonator designs.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

DOE OSTI2016

Diffractive optical elements for transformation of modes in lasers

43 PARTICLE ACCELERATORS↗

DOE OSTI2019

Connectors for multicore optical fibers and methods thereof

The present invention relates to optical coupling systems that employ a multicore optical fiber. The system can be employed with two multicore optical fibers or with a single multicore optical fiber for use with an optical device. In particular, the system includes connectors having a lens assembly configured to relay optical signals and a ferrule to position the lens assembly. Additional details for making and using such systems are described herein.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2019

Photoconductive device with optical concentrator

A photonic device having wide bandgap (WBG) materials which change electrical behaviors in response to low-intensity light is disclosed. The device comprises an optical waveguide located in an optical path of light to receive the light and to spatially confine the received light as guided light at a higher optical intensity than the received light; a wide bandgap (WBG) material located in an optical path of the guided light output by the optical waveguide; and two electrodes formed at two different locations on the WBG material to provide two electrical contacts of an electrical path within the WBG material, wherein the WBG material exhibits an electrical conductivity that varies with a level of the guided light output by the optical waveguide to turn on or off the electrical path between the two electrodes.

Sampayan, Stephen↗

DOE OSTI2020

Method of authenticating integrated circuits using optical characteristics of physically unclonable functions

A method and apparatus for reading unique identifiers of an integrated circuit. The unique identifiers may be physically unclonable functions (PUFs), formed by high energy ions implanted into semiconductor material of the integrated circuit. The method may include electrically or optically stimulating each of the PUFs and sensing with an optical sensor optical characteristics of resulting light emitted from the PUFs. Then the method may include comparing values associated with the optical characteristics of the PUFs with groups of stored values in a circuit database. Each of the groups of stored values may be associated with optical characteristics of PUFs of a known authentic circuit. The method may then include the controller providing verification of authenticity of the integrated circuit when each of the values associated with the optical characteristics of the PUFs match the stored values of at least one of the groups in the circuit database.

42 ENGINEERING↗

DOE OSTI2020

The Simons Observatory: Modeling Optical Systematics in the Large Aperture Telescope

We present geometrical and physical optics simulation results for the Simons Observatory Large Aperture Telescope. This work was developed as part of the general design process for the telescope; allowing us to evaluate the impact of various design choices on performance metrics and potential systematic effects. The primary goal of the simulations was to evaluate the final design of the reflectors and the cold optics which are now being built. We describe non-sequential ray tracing used to inform the design of the cold optics, including absorbers internal to each optics tube. We discuss ray tracing simulations of the telescope structure that allow us to determine geometries that minimize detector loading and mitigate spurious near-field effects that have not been resolved by the internal baffling. We also describe physical optics simulations, performed over a range of frequencies and field locations, that produce estimates of monochromatic far field beam patterns which in turn are used to gauge general optical performance. Finally, we describe simulations that shed light on beam sidelobes from panel gap diffraction.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2022

Method of evaluating pH using a metallic nanoparticle incorporated nanocomposite-based optical pH sensor

A method for evaluating the pH of an aqueous solution by utilizing the optical properties of a pH sensing material comprised of plurality of optically active nanoparticles dispersed in matrix material. The optically active nanoparticles have an electronic conductivity greater than about 10−1 S/cm and generally have an average nanoparticle diameter of less that about 500 nanometers, and the matrix material is a material which experiences a change in surface charge density over a pH range from 2.0 to 12.0 of at least 1%. The method comprises contacting the pH sensing material and the aqueous solution, illuminating the pH sensing material, and monitoring an optical signal generated through comparison of incident light and exiting light to determine the optical transmission, absorption, reflection, and/or scattering of the pH sensitive material. The optical signal of the pH sensitive material varies in response to the pH of the aqueous solution.

Ohodnicki, Jr., Paul R.↗

DOE OSTI2023

Digital fabrication of a small diameter polymer optical waveguide

A novel polymer optical waveguide and method of manufacturing is presented herein. A digitally manufactured process is described which utilizes a micro-dispensed UV optical adhesive as the contour guiding cladding, a fused deposition modeling technology for creating a core, and a subtractive laser process to finish the two ends of the optical interconnect. The optical waveguide can be printed directly on a circuit board in some embodiments. Alternatively, using a slightly modified process including a step to bond the optical fiber to the substrate, the optical interconnect can be manufactured on a flexible substrate.

Bhethanabotla, Venkat Rama↗

DOE OSTI2023

Optics Studies for Multipass Energy Recovery at CEBAF: ER@CEBAF

Energy recovery linacs (ERLs), focus on recycling the kinetic energy of electron beam for the purpose of accelerating a newly injected beam within the same accelerating structure. The rising developments in the super conducting radio frequency technology, ERL technology has achieved several noteworthy milestones over the past few decades. In year 2003, Jefferson Lab has successfully demonstrated a single pass energy recovery at the CEBAF accelerator. Furthermore, they conducted successful experiments with IR-FEL demo and upgrades, as well as the UV FEL driver. This multi-pass, multi-GeV range energy recovery demonstration proposed to be carried out at CEBAF accelerator at Jefferson Lab focuses on demonstrating highest energy recovery in super conducting linac in the low-current range. Continuous electron beam accelerate up to 7.5 GeV within 5-passes and decelerate in the next 5-passes recovering RF energy and dumps at a low energy dump. The beamline optics design for recirculating linacs require special attention to avoid beam instabilities due to RF wakefields. Usually, multi-pass linac beam lines require stronger focusing at lower energies as that is necessary to avoid beam breakup (BBU) instabilities, even with this small beam current. The CEBAF linac optics optimization is focused on balancing over-focusing at higher energies and beta excursions at lower energies. The race-track-shaped geometry of CEBAF accelerator allows its linacs to accommodate multiple energy beams simultaneously, while individual recirculating arcs transporting one beam energy, are shared between accelerating/decelerating beams. For the linac optics optimization process, an extended strategy is used that is originally used in 6-pass Recirculating Linac design of the LHeC, to represent the ten passes through a single linac. Using proper mathematical expressions, linac optics optimization can be achieved with evolutionary genetic algorithms, with Multi-Objective optimization. This thesis introduces a CEBAF optics redesign tailored to accommodates the ER@CEBAF multi-pass ER scheme. The isochronous arcs were retuned to match into optics solutions for optimized 10-pass linacs. Within this work, a single bunch particle tracking analysis presented here focuses on the further improvements of the beamline and beam transportation.

Neththikumara, Isurumali↗

DOE OSTI2025

Nickel-incorporated Oxide Composites for Fiber-Optic Based Gas Sensing

Numerous high-value applications within the energy sector involve environmental conditions that are incompatible with traditional sensor technology due to degradation of electrical interconnects, packaging, or the sensors themselves. These can include chemically harsh conditions, high temperature operation, or the presence of electromagnetic interference due to high voltage. The fiber optic platform, constructed of robust, electrically insulating glass or single crystal oxides, offers a versatile and often low cost per node solution to this problem, especially with the integration of distributed sensing techniques such as optical time-domain and frequency-domain reflectometry (OTDR, OFDR). A major challenge of gas and chemical sensing on the optical fiber platform is the fabrication of robust and stable sensing materials that interact quickly and reversibly to the presence of the target analytes. In this work, we discuss the utilization of nickel-incorporated oxides on evanescent-field optical fiber sensors for gas sensing under harsh conditions relevant to multiple energy infrastructure applications. This paper will discuss a Ni/GDC (Ni / Gd-doped ceria) based sensing layer targeting conditions relevant for high-temperature (up to at least 800oC) hydrogen sensing applications (e.g., for operation within a solid oxide fuel cell or electrolyzer). The impact of hydrogen at elevated temperatures on the optical properties of Ni/GDC will be shown and the material mechanisms for the optical response will be discussed.

gas sensors↗

DOE OSTI2023

Quantifying optical loss of high-voltage degradation modes in photovoltaic modules using spectral analysis

The direct current bias for photovoltaic (PV) modules interconnected in series-strings may include both high voltage negative (“HV-”) and positive (“HV+”) polarity with respect to the electrical ground. Multiple degradation modes, resulting in quantifiable optical loss, were found to occur during HV-/HV+ sequential stress, including corrosion of the external glass surface, encapsulant delamination (at its interfaces with the glass and the PV cell), internal haze formation (resulting from a chemical interaction between the glass and the encapsulant), corrosion and migration of the gridlines, and corrosion of the silicon nitride (Si x N y ) antireflective coating on the cell. The effects of these separate modes were examined using monolithic (e.g., glass or PV cell) and laminated-coupon (glass/encapsulant/glass or glass/encapsulant/cell/encapsulant/backsheet) specimens. Characterizations during and after unbiased accelerated testing at 85°C/85% relative humidity included spectrophotometry, optical microscopy, electron microscopy, and ellipsometry. For some module components (i.e., the glass and the Si x N y coating), the optical performance was determined through iterative analysis of empirical measurements. Concentrating on just their spectral effect, a novel model was then developed to estimate the transfer of light to the PV cell and the return of light from the PV module with simultaneous degradation mechanisms, which was compared with a mini-module previously subjected to HV-/HV+ stress. Here the model suggests that one third of the current loss observed for the mini-module can be attributed to the optical degradation of the packaging materials. The dominant degradation modes include encapsulant delamination and corrosion of the Si x N y coating. Recommendations are given so that the optical model may be improved relative to accelerated testing and validated relative to field aging.

14 SOLAR ENERGY↗

DOE OSTI2019

Simulation and research of few-mode optical fiber DMD degradation due to geometry deviation from optimized form

This work presents an alternative fast and simple method for the design of a graded refractive index profile of silica few-mode optical fibers (FMFs) with enlarged core diameter that extremely improves mode effective area, and low differential mode delay (DMD). We demonstrate some results of refractive index profile optimization for 16-LP-mode FMF with enlarged core diameter up to 42 μm and mode effective area more 130 μm{sup 2} under DMD reduction less 120 ps/km all over “C”-band and less 40 ps/km at λ = 1550 nm region. We also propose approach for simulation of the deviation of “real” optical fiber geometry from the optimized form and rigorous method for analysis of large core complicated optical fiber. Here, FMF core asymmetrical ellipticity together with the refractive index profile distortions were considered. They were set and simulated by data from reports of the real commercially available laser-optimized multimode optical fibers of TIA/ISO Cat. OM2+/OM3 refractive index profile measurements, performed by lab optical fiber analyzer kit. We present results of researches of considered FMF DMD spectral curve degradation due to described core geometry deviation from the optimized form. It was noticed, that unlike to only refractive index local fluctuations, FMF core non-circularity strongly distorts higher-order mode field distribution that affects to spectral mode delay curves and may lead to critical total DMD increasing.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

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