We present a photoacoustic tomography-guided diffuse optical tomography approach using a hand-held probe for detection and characterization of deeply-seated targets embedded in a turbid medium. Diffuse optical tomography guided by coregistered ultrasound, MRI, and x ray has demonstrated a great clinical potential to overcome lesion location uncertainty and to improve light quantification accura...

Using the observed temperature dependence of a-Si:H photon absorption spectrum and the weak-phonon interaction second-order transition theory, phonon-coupling enhanced photon absorption is predicted for a-Si-Ge and a-Si-Sn alloys. The ab initio calculated electron and phonon properties of the alloyed amorphous phase show minimally altered electronic states and significant redshifted phonon ener...

Two sets of hydrogenated microcrystalline silicon thin-film samples were prepared by Plasma Enhanced Chemical Vapor Deposition (PECVD) technique at different deposition conditions of excited power and pressure. The correlation between the crystalline volume fraction for the samples determined from Raman spectra and the excited power, pressure, absorption coefficient, refractive index and optica...

Optical limiting and thermo-optic properties of C60 in toluene are studied using 532 nm, 9 ns pulses from a frequency-doubled Nd:YAG laser. Optical limiting studies in these fullerene molecules lead to the conclusion that reverse saturable absorption is the major mechanism for limiting properties in these molecules. Thermal lensing measurements are also performed in fullerene solutions. The qua...

InN films with free electron concentrations ranging from mid-10 to mid-10 cm have been studied using optical absorption, Hall effect, and secondary ion mass spectrometry. The optical absorption edge covers a wide energy range from the intrinsic band gap of InN of about 0.7 to about 1.7 eV which is close to the previously accepted band gap of InN. The electron concentration dependence of the opt...

ZnO nanocrystals were successfully fabricated by wet-chemical method. Optical properties of excitons confined in ZnO nanocrystals were studied by measuring both optical absorption and photoluminescence spectra. Absorption due to free excitons was clearly observed whereas strong PL lines were recorded in the UV region at around the exciton absorption energy. Red-shift of optical features with in...

As is well known the absorption of circularly polarized light in semiconductors results in optical orientation of electron spins and helicity-dependent electric photocurrent, and the absorption of linearly polarized light is accompanied by optical alignment of electron momenta. Here we show that the absorption of unpolarized light in a quantum well (QW) leads to generation of a pure spin curren...

By monitoring the nonlinear absorption of picosecond laser pulses as a function of lattice temperature, we identify four-photon absorption in bulk InAs. Optical bandgap scaling of this process is consistent with a calculation obtained from fourth-order perturbation theory for allowed–allowed–allowed–forbidden transitions. A model of nonlinear absorption based on laser-induced impact ionization ...