One of the primary difficulties in the implementation of organic-dye-based random lasers is the tendency of organic dyes to irreversibly photodecay. In this Letter, we report the observation of "reversible" photodegradation in a Rhodamine 6G and ZrO2 nanoparticle-doped polyurethane random laser. We find that during degradation, the emission broadens, redshifts, and decreases in intensity. After...

In this study, a new simple model based on the classical treatment of lattice vibrations and the Franck-Condon principle is developed to describe the shape of thermoluminescence (TL) emission bands of crystalline solids. According to developed model, shape of the emission band has a Gaussian form and depends on just two physical parameters: peak energy E0 and broadening of emission spectra U. I...

Doppler analysis of flow in intracranial arteries is now possible using a 2 MHz probe allowing sufficient penetration of bone to obtain signals noninvasively. Thirty-two normal subjects, and 11 patients with cerebrovascular diseases including vasospasm following subarachnoid hemorrhage, middle cerebral artery stenosis, and extracranial internal carotid artery stenosis were studied by transcrani...

Recent measurements of the p+p− invariant-mass distribution at RHIC show a shifted peak for the r meson in 100A GeV in peripheral Au+Au and even in p+p collisions. A recent theoretical study based on a picture of in-medium production rates of pions showed that a large shift could result from a combination of the Boltzmann factor and the collisional broadening of the r. Here we argue that the tw...

By spectrally and temporally reshaping the gain-window of a traveling-wave semiconductor optical amplifier (TWSOA) with a backward injected multi- or single-wavelength inverse-optical-comb, we theoretically and experimentally investigate the dynamic frequency chirp of the all-optical 10GBit/s Return-to-Zero (RZ) data-stream format-converted from the TWSOA under strong cross-gain depletion schem...

We investigate dynamical scaling properties in the integer quantum Hall effect for non-interacting electrons at zero temperature, by means of the frequency-induced peak broadening of the dissipative longitudinal conductivity σ xx (ω). This quantity is calculated numerically in the lowest Landau level for various values of the Fermi energy E, of the frequency ω, and of the system size L. Data fo...

We observe pulse breakup for 650-fs pulses propagating through 9 m of optical fiber followed by an InGaAsP amplifier. The pulses are broadened by a factor of two, and a second peak appears at about 2 ps after the main peak. To identify the responsible mechanisms, we solve numerically the propagation equations including nonlinear carrier dynamics and gain dispersion. We attribute the broadening ...

We detect a significant broadening in the wings of the 401 Hz peak in the power spectrum of the accreting millisecond binary pulsar SAX J1808.4-3658. This feature is consistent with the convolution of the red noise present in the power spectrum with the harmonic line. We conclude that the flux modulated by the spin period shows aperiodic variability similar to the red noise in the overall flux,...

We predict the spontaneous modulated emission from a pair of exciton-polariton condensates due to coherent (Josephson) and dissipative coupling. We show that strong polariton-polariton interaction generates complex dynamics in the weak-lasing domain way beyond Hopf bifurcations. As a result, the exciton-polariton condensates exhibit self-induced oscillations and emit an equidistant frequency co...

Self Phase Modulation (SPM) and Stimulated Raman Scattering (SRS) in silicon waveguides have been observed and will be discussed theoretically using a modified Nonlinear Schrödinger Equation. The high optical peak powers needed for the experiments were obtained by coupling sub-picosecond (200fs) transform limited pulses with a spectral width of 12nm into a single mode silicon waveguide. Spectra...