Physical Sciences

Counting of particles is not necessary.

A method of using ellipsometry or polarization analysis of light in total internal reflection of a surface to determine the number density of gold nanoparticles on a smooth substrate has been developed. The method can be modified to enable determination ...
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A concept is proposed of the thermally driven Josephson effect in superfluid helium. Heretofore, the Josephson effect in a superfluid has been recognized as an oscillatory flow that arises in response to a steady pressure difference between two superfluid reservoirs separated by an array of submicron-sized orifices, which act in ...
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The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ...
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This report presents a computational- simulation study of effects of perturbation wavelengths and initial Reynolds numbers on the transition to turbulence of a heptane/ nitrogen mixing layer at supercritical pressure. The governing equations for the simulations were the same as those of related prior studies reported in NASA Tech Briefs. ...
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Phase matching is necessary for exploitation of nonlinear optical phenomena.

Phase matching of diverse electromagnetic modes (specifically, coexisting optical and microwave modes) in a whispering-gallery-mode (WGM) resonator has been predicted theoretically and verified experimentally. Such phase matching is necessary for storage of microwave/terahertz and optical ...
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Three-wave mixing, resonance, and low loss would result in high efficiency.

Microwave-to-optical frequency converters based on whispering-gallery-mode (WGM) resonators have been proposed as mixers for the input ends of microwave receivers in which, downstream of the input ends, signals would be processed photonically. A frequency converter ...
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One receiver would have the functionality of multiple traditional heterodyne microwave receivers.

In wide-band microwave receivers of a type now undergoing development, the incoming microwave signals are electronically preamplified, then frequency-up-converted to optical signals that are processed photonically before being detected. This approach differs from the ...
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Receivers containing these devices are contemplated for astronomical and military uses.

Progress has been made toward solving some practical problems in the implementation of terahertz-to-optical frequency converters utilizing whispering-gallery-mode (WGM) resonators. Such frequency converters are expected to be essential parts of non-cryogenic terahertz-radiation receivers that are, ...
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Differences between temperature-dependent frequencies of resonances would be measured.

A proposed technique for measuring temperature would exploit differences between the temperature dependences of the frequencies of two different electromagnetic modes of a whispering-gallery-mode (WGM) optical resonator. An apparatus based on this technique was originally intended to ...
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A smaller laser slab can be made to perform comparably to a larger one.

A four-pass optical coupler affords increased (in comparison with related prior two-pass optical couplers) utilization of light generated by a laser diode in side pumping of a solid-state laser slab. The original ...
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Lenses mode-matched to the laser beams would be moved axially within an afocal optical subassembly.

A provision for controlled variation of the divergence of a laser beam or of multiple parallel laser beams has been incorporated into the design of a conceptual free-space optical-communication station from ...
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This method offers advantages over related prior Ramanspectroscopy- based methods.

A method of optical thermometry, now undergoing development, involves low-resolution measurement of the spectrum of spontaneous Raman scattering (SRS) from N₂ and O₂ molecules. The method is especially suitable for measuring temperatures ...
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