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Physics

Optical physics and communications

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Displaying 401 - 425 of 861

Ultrafast Laser Eyewear Protection: Measurements and Precautions

September 25, 2017
Author(s)
Christopher J. Stromberg, Joshua A. Hadler, Brian Alberding, Edwin J. Heilweil
Ultrafast laser systems are becoming more widespread throughout the research and industrial communities yet eye protection for these high power, bright pulsed sources still require scrupulous characterization and testing before use. Femtosecond lasers

Bound Electron Nonlinearity Beyond the Ionization Threshold

September 18, 2017
Author(s)
Jared K. Wahlstrand, Sina Zahedpour, H M. Milchberg
Using supercontinuum spectral interferometry, we measure the ionization induced optical phase shift in three noble gases and nitrogen and oxygen. Results largely support the standard model of filamentation.

Electromagnetic Scattering from Individual Crumpled Graphene Flakes: A Characteristic Modes Approach

September 14, 2017
Author(s)
Edward J. Garboczi, Jack F. Douglas, Luis Fernando Vargas Lara, Ahmed M. Hassan, Deb Chatterjee, Kalyan Durbhakula, Md Gaffar
Graphene flakes in real composites are rarely perfectly flat, and often exhibit complicated crumpled shapes. Therefore, the goal of this work was to quantify the electromagnetic scattering characteristics of individual crumpled graphene flakes with shapes

ESTABLISHING BRDF CALIBRATION CAPABILITIES THROUGH SHORTWAVE INFRARED

September 5, 2017
Author(s)
Catherine C. Cooksey, Georgi T. Georgiev, James Butler, Kurtis J. Thome, Leibo Ding
Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Distribution Functions (BRDFs) of the laboratory and flight diffusers used in their pre-flight and on

Optical spin transfer and spin-orbit torques in thin-film ferromagnets

August 30, 2017
Author(s)
Junwen Li, Paul M. Haney
We study the optically induced torques on thin film ferromagnetic layers under excitation by circularly polarized light. We include Rashba spin-orbit coupling and assume an out-of-plane magnetization, and consider incident light with an in-plane component

Towards integrated superconducting detectors on lithium niobate waveguides

August 29, 2017
Author(s)
Jan P. Hoepker, Moritz Bartnick, Evan Meyer-Scott, Frederik Thiele, Stephan Krapick, Nicola Montaut, Matteo Santandrea, Harald Herrmann, Sebastian Lengeling, Raimund Ricken, Victor Quiring, Torsten Meier, Adriana Lita, Varun Verma, Thomas Gerrits, Sae Woo Nam, Christine Silberhorn, Tim J. Bartley
Superconducting detectors are now well-established tools for low-light optics, and in particular quantum optics, boasting high-efficiency, fast response and low noise. Similarly, lithium niobate is an important platform for integrated optics given its

A Photonic MEMS Accelerometer with a Low-Finesse Hemispherical Microcavity Readout

August 13, 2017
Author(s)
Yiliang Bao, Feng Zhou, Thomas W. LeBrun, Jason J. Gorman
This paper describes the design, fabrication, and testing of a photonic MEMS accelerometer that uses a hemispherical microcavity to transduce the motion of the proof mass. The cavity design provides stable operation that is relatively tolerant of

Narrowband Optomechanical Refrigeration of a Chiral Bath

August 7, 2017
Author(s)
Jacob M. Taylor, Kim Seunghwi, Xu Xunnong, Gaurav Bahl
The transport of sound and heat, in the form of phonons, is fundamentally limited by disorder-induced scattering. In electronic and optical settings, introduction of chiral transport - in which carriers have unidirectional propagation - provides robustness

Phase mask-based multimodal superresolution microscopy

July 6, 2017
Author(s)
Ryan Beams, Jeremiah W. Woodcock, Jeffrey W. Gilman, Stephan J. Stranick
We demonstrate a multimodal superresolution microscopy technique based on a phase masked excitation beam in combination with spatially filtered detection. The theoretical foundation for calculating the focus from a non-paraxial beam with an arbitrary

Silicon Micromachined Capacitive Force Scale: The Way to Improved Radiation Pressure Sensing

July 2, 2017
Author(s)
Ivan Ryger, Paul A. Williams, Nathan A. Tomlin, Alexandra B. Artusio-Glimpse, Michelle S. Stephens, Matthew T. Spidell, John H. Lehman
Measurement of high optical power using radiation pressure sensing [1] is attractive for its non-absorbing power measurment allowing compact sensor dimensions, faster response times and negligible optical power dissipation compared to standard thermal

Abrupt dependence of ultrafast extrinsic photoconductivity on er fraction in gaas:er

July 1, 2017
Author(s)
Elliott Brown, A. Mingardi, W-D. Zhang, Ari Feldman, Todd E. Harvey, Richard Mirin
We present a study of room-temperature, ultrafast photoconductivity associated with strong, sub-bandgap, resonant absorption around lamba} = 1550 nm in three MBE-grown GaAs epitaxial layers heavily doped with Er at concentrations of ≅2.9 x 10 18 (control

A method to extrapolate the diffuse upwelling radiance attenuation coefficient to the surface as applied to the Marine Optical Buoy (MOBY)

June 30, 2017
Author(s)
Kenneth Voss, Howard Gordon, Stephanie J. Flora, B. Carol Johnson, Mark A. Yarbrough, Michael Feinholz, Terrance Houlihan
The upwelling radiance attenuation coefficient (KLu) in the upper 10 m of the water column can be significantly influenced by inelastic scattering processes, and thus will vary even with homogeneous water properties. The Marine Optical BuoY (MOBY), the

Frequency response of the external quantum efficiency in multijunction solar cells

June 29, 2017
Author(s)
Nicolas Marquez Peraca, D T. Bilir, Behrang Hamadani
The frequency dependence of the external quantum efficiency (EQE) of high-quality multijunction solar cells was examined by the modulated photocurrent spectroscopy method via an optical setup comprised of a light-pipe-coupled compact LED array. The optical

Immersion coefficient for the Marine Optical BuoY (MOBY) radiance collectors

June 28, 2017
Author(s)
Michael Feinholz, B. Carol Johnson, Kenneth Voss, Mark A. Yarbrough, Stephanie J. Flora
The immersion coefficient accounts for the difference in calibration for a radiometer placed in the air versus water or another medium. The immersion coefficient for the radiance collectors on the Marine Optical BuoY (MOBY) were modeled and measured. The

Neutral and Charged Inter-Valley Biexcitons in Monolayer MoSe2

June 28, 2017
Author(s)
Lixiang Xu, Judith Specht, Philip Nagler, Kha Tran, Akshay Singh, Chandriker K. Dass, Andreas Knorr, Xiaoqin Li, Galan Moody
In atomically thin transition metal dichalcogenides (TMDs), reduced dielectric screening of the Coulomb interaction leads to strongly correlated many-body states, including excitons and trions, that dominate the optical properties. Higher-order states

Software for complete mode structure analysis of a light field

June 26, 2017
Author(s)
Ivan A. Burenkov, Sergey V. Polyakov
We present a software package aimed at simulating photon-number probability distributions of a range of naturally occurring classical and non-classical states of light. This software can generate arbitrary probability distributions based on the known mode

Concave silicon micromirrors for stable hemispherical optical microcavities

June 23, 2017
Author(s)
Yiliang Bao, Feng Zhou, Thomas W. LeBrun, Jason J. Gorman
A detailed study of the fabrication of silicon concave micromirrors for hemispherical microcavities is presented that includes fabrication yield, surface quality, surface roughness, cavity depth, radius of curvature, and the aspect ratio between the cavity

Approaches for Characterizing Nonlinear Mixtures in Hyperspectral Imagery

June 21, 2017
Author(s)
Robert S. Rand, Ronald G. Resmini, David W. Allen
This study considers a physics-based and a kernel-based approach for characterizing pixels in a scene that may be linear (areal mixed) or nonlinear (intimately mixed). The physics-based method is based on earlier studies that indicate nonlinear mixtures in

Tip Enhanced Raman Scattering of Graphene

June 20, 2017
Author(s)
Ryan Beams
This article reviews the mechanism of tip enhanced Raman spectroscopy (TERS) and its importance for characterizing graphene. The theoretical foundation of TERS and experimental implementation are discussed. Conventionally, Raman scattering is treated as a

Wake Mode Sidebands and Instability of Modelocked Lasers with Slow Saturable Absorbers

June 14, 2017
Author(s)
Shaokang Wang, Stefan Droste, Laura C. Sinclair, Ian R. Coddington, Nathan R. Newbury, Curtis R. Menyuk
Passively modelocked lasers with semiconductor saturable absorption mirrors (SESAMs) are attractive comb sources since they can be made environmentally stable, but they become unstable when the group velocity dispersion is too low or the gain is too high
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