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The validity of the displacement discontinuity model for elastic wave propagation across and along fractures is related to the spacing of asperities in fractures. In this paper, the transition from the displacement-discontinuity regime to the resonant scattering of Rayleigh waves is explicitly observed for waves propagating along synthetic fractures. The(More)
We introduce spinning-disc Picometrology which is designed to measure complex refractive index of ultra-thin and size-limited sample deposited on a solid surface. Picometrology is applied to measure the refractive index of graphene on thermal oxide on silicon. The refractive index varies from ñg = 2.4-1.0i at 532 nm to ñg = 3.0-1.4i at 633 nm at room(More)
Common-path in-line shearing interferometry, combined with pixel-array imaging, provides a surface metrology that achieves 15 pm surface height resolution. An eighth-wave thermal oxide on silicon generates a reference wave locked in the condition of phase quadrature for phase-to-intensity conversion that makes surface height or index variations directly(More)
Finite-size scaling analysis applied to single fractures with weakly correlated aperture distributions reveals a fundamental scaling relationship between fracture sti↵ness and fracture fluid flow. Computer simulations extract the dynamic transport exponent, which is required to collapse the flow-sti↵ness relationships onto a universal scaling function. Near(More)
This review covers a spectrum of optoelectronic properties of and uses for semi-insulating semiconductor heterostructures and thin films, including epilayers and quantum wells. Compensation by doping, implantation, and nonstoichiometric growth are described in terms of the properties of point defects and Fermi level stabilization and pinning. The principal(More)
We present depth-resolved coherence-domain images of living tissue using a dynamic holographic semiconductor film. An AlGaAs photorefractive quantum-well device is used in an adaptive interferometer that records coherent backscattered ͑image-bearing͒ light from inside rat osteogenic sarcoma tumor spheroids up to 1 mm in diameter in vitro. The data consist(More)
The photoexcited carrier lifetimes in ex situ-annealed low temperature growth GaAs are measured with a femtosecond transient absorption experiment. The study encompassed two low temperature growth GaAs films with approximately 0.3% and 0.9% excess arsenic incorporated during growth. The observed lifetimes are found to be a function of the spacing of arsenic(More)
BACKGROUND We describe a direct-detection immunoassay that uses high-speed optical interferometry on a biological compact disc (BioCD). METHODS We fabricated phase-contrast BioCDs from 100-mm diameter 1.1-mm thick borosilicate glass disks coated with a 10-layer dielectric stack of Ta2O5/SiO2 that serves as a mirror with a center wavelength at 635 nm. The(More)
The photorefractive properties of semi-insulating AlGaAs-GaAs multiple quantum wells are described for the transverse Franz-Keldysh geometry with the electric field in the plane of the quantum wells. Combining the strong electroabsorption of quantum-confined excitons with the high resistivity of semi-insulating quantum wells yields large nonlinear optical(More)
We demonstrate a laser-based adaptive ultrasonic homodyne receiver using dynamic holography in AlGaAs/GaAs photorefractive multiple quantum wells. The dynamic hologram acts as an adaptive beamsplitter that compensates wavefront distortions in the presence of speckle and requires no path-length stabilization. The photorefractive quantum wells have the unique(More)