Absorbing layers are sometimes required to be impractically thick in order to offer an accurate approximation of an absorbing boundary condition for the Helmholtz equation in a heterogeneous medium. It is always possible to reduce an absorbing layer to an operator at the boundary by layer-stripping elimination of the exterior unknowns, but the linear algebra involved is costly. We propose to by...

The possibility of using the self-induced transparency effect to achieve laser mode locking has been discussed since the late 1960s but has never been observed. In prior work, we proposed that quantum cascade lasers are the ideal tool to realize self-induced transparency mode locking due to their rapid gain recovery times and relatively long coherence times, and because it is possible to interl...

In absorption spectroscopy, absorption features impressed on the spectrum of a continuum background source are interpreted in terms of conditions in an absorbing foreground medium. If the opacity per ion for a particular transition beginning from some initial state is known, then the areal density (i.e., the path integral of the density along the path of the continuum propagation) of ions in th...

The applicability and limits of time-resolved transillumination to determine the internal details of biological tissues are investigated by phantom experiments. By means of line scans across a sharp edge, the spatial resolution (Δx) and its dependence on the time-gate width (Δt) can be determined. Additionally, measurements of completely absorbing bead pairs embedded in a turbid medium demonstr...

An approximate analytic model is presented to describe spatial structure of refracted electromagnetic field arising at oblique incidence of a Gaussian beam on a plane boundary of an absorbing homogeneous medium. The analytic solution is obtained by asymptotic approximation of a Fourier field integral under the condition of great beam width in comparison with a wavelength (the geometrical-optics...

We introduce the concept of Cavity Enhanced Self-Absorption Spectroscopy (CESAS), a new sensitive diagnostic tool for analyzing light-emitting samples. The technique works without an additional light source and its implementation is straight forward. In CESAS, a sample (plasma, flame, or combustion source) is located in an optically stable cavity consisting of two high reflectivity mirrors, and...

Abstrae--The normal-mode-expansion technique is used to obtain a semi-analytical solution for the angular distribution of radiation at any optical distance within a linearly anisotropicscattering, absorbing, emitting, non-isothermal, gray medium between two parallel reflecting boundaries. Both conservative and nonconservative cases are considered. The general problem is decomposed into simpler ...

X iv :q ua nt -p h/ 05 10 11 3 v3 22 M ar 2 00 6 Heralded single-photon generation using imperfect single-photon sources and a two-photon-absorbing medium Thomas Konrad∗, Artur Scherer, Michael Nock, and Jürgen Audretsch Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany Abstract We propose a setup for a heralded, i.e. announced generation of a pure single-photon state given tw...

Two-dimensional numerical study of flow and temperature fields for laminar natural convection and radiation in the inclined cavity is performed in the present work. The walls of the square cavity are assumed kept at constant temperatures. An absorbing, emitting, and scattering gray medium is enclosed by the opaque and diffusely emitting walls. The set of governing equations, including conservat...

Using the RXTE PCA we discovered dips in the X-ray light curves of the black-hole candidate GRO J1655−40 during outburst. They are short (∼minute) and deep (down to ∼8% of the out-of-dip intensity). Similar kind of dips were found in 90 s measurements of the RXTE ASM during the same outburst. The occurrences of the dips are consistent with the optically determined orbital period, and were found...