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1.
Appl Opt ; 56(11): E72-E76, 2017 Apr 10.
Article in English | MEDLINE | ID: mdl-28414344

ABSTRACT

As part of the Deepwater Horizon toxicity testing program, a number of laboratories generated oil slicks in the laboratory to study potential toxic effects of these oil slicks on aquatic organisms. Understanding the details of how these slicks affect aquatic organisms requires careful correlation between slick thickness and the observed detrimental effects. Estimating oil film thickness on water can be challenging since the traditional color-based technique used in the field is very imprecise. Also, as we demonstrate here, the films formed on the water surface are highly nonuniform on a microscale level, and thus uniform thin film thickness measurement techniques based on optical interference do not work. In this paper, we present a method that estimates the local thickness of weathered oil slicks formed on artificial seawater using light transmission and Beer-Lambert's law. Here, we demonstrate results of careful calibration together with the actual thickness estimation. Due to the heterogeneity of the slicks formed, we present slick thickness as a range of thicknesses collected from multiple points within the oil slick. In all the experiments we used oil samples provided by the Natural Resource Damage Assessment toxicity testing program for the Deepwater Horizon oil spill. Therefore, this study has an important practical value and successfully addresses unique challenges related to measurements involving complex, viscous, paste-like heterogeneous substances such as weathered crude oil.

2.
Appl Opt ; 48(14): 2613-8, 2009 May 10.
Article in English | MEDLINE | ID: mdl-19424379

ABSTRACT

We present an optical resonance sensor capable of measurement of refractive index in highly nonhomogeneous materials. Traditional optical resonance sensors fail when the size of particles is comparable with the wavelength (100 nm and larger). Our new nanoengineered design allows incorporation of a highly delocalized mode into a resonance structure. The sensing depth of the device was measured to be 1 mum, the largest reported in the literature as far as we know, with a quality factor of 500. We demonstrate two applications.


Subject(s)
Manufactured Materials/analysis , Nanostructures/chemistry , Nanostructures/ultrastructure , Nanotechnology/instrumentation , Optical Devices , Refractometry/instrumentation , Equipment Design , Equipment Failure Analysis , Materials Testing
3.
Nat Nanotechnol ; 3(11): 660-5, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18989331

ABSTRACT

Future optical data transmission modules will require the integration of more than 10,000 x 10,000 input and output channels to increase data transmission rates and capacity. This level of integration, which greatly exceeds that of a conventional diffraction-limited photonic integrated circuit, will require the use of waveguides with a mode confinement below the diffraction limit, and also the integration of these waveguides with diffraction-limited components. We propose to integrate multiple silver nanowire plasmonic waveguides with polymer optical waveguides for the nanoscale confinement and guiding of light on a chip. In our device, the nanowires lay perpendicular to the polymer waveguide with one end inside the polymer. We theoretically predict and experimentally demonstrate coupling of light into multiple nanowires from the same waveguide, and also demonstrate control over the degree of coupling by changing the light polarization.


Subject(s)
Electrons , Nanotechnology/instrumentation , Nanowires/chemistry , Optical Fibers , Electronics/instrumentation , Equipment Design , Light , Nanowires/ultrastructure , Optics and Photonics/instrumentation , Polymers/chemistry , Scattering, Radiation , Silver/chemistry
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