Doppler broadening

About: Doppler broadening is a research topic. Over the lifetime, 5509 publications have been published within this topic receiving 92552 citations.

Direct numerical method to solve radiation trapping problems with a Doppler-broadening mechanism for partial frequency redistribution

Abstract: We present a numerical method for solving the Holstein-Biberman-Payne equation with Doppler frequency redistribution. The method is based on direct time propagation of the initial distribution of excited atoms, employing the split-propagation technique. It allows a precise study of various aspects of radiation transfer phenomena occurring in an arbitrary convex three-dimensional spatial region, driven by external conditions with arbitrary time dependencies. We present some results obtained for slab and spherically shaped geometries and compare them to results from other evaluation methods. The efficiency of the method is demonstrated by determining the intensity of radiation escaping the gas cell in afterglow experiments.

Enhancing the index of refraction under convenient conditions

Abstract: We investigate the possibility of increasing the achievable index of refraction and the slope of the dispersion while simultaneously minimizing absorption in a driven two-level system. The analysis is performed non-linearly in both the probing laser field and Doppler and collision broadening have been incorporated for the sake of a realistic treatment. We compare the achievable index of refraction without absorption quantitatively with known results of several favorable three- and four-level systems, find our system less sensitive to Doppler broadening in a collinear set-up of both fields and apply our considerations to the particular example of caesium.

Resonant tunneling and extreme brightness from diamond field emitters and carbon nanotubes

Abstract: We report new results from field emission microscopy studies of multiwall carbon nanotubes and from energy spectrum measurements of beams from diamond field emitters In both systems, we find that resonant tunneling through adsorbed species on the emitter surface is an important and sometimes dominant effect For diamond emitters our observations include order-of-magnitude emission enhancement without spectral broadening, complex spectral structure, and sensitivity of that structure to the applied electric field For carbon nanotubes we have observed electron beams from individual adsorbates which are estimated to approach the maximum beam brightness allowed by Pauli exclusion

Spectral broadening of stochastic light intensity-smoothed by a saturated semiconductor optical amplifier

Abstract: We present calculations of the intensity smoothing of stochastic light by a semiconductor optical amplifier (SOA). We predict spectral changes of the light that are due to amplitude-to-phase coupling in the gain medium. The intensity smoothing of noisy optical signals with an SOA carries a penalty of spectral broadening (increased phase noise) that increases with increasing alpha parameter (linewidth enhancement factor). The spectral broadening also increases with increasing strength of the intensity fluctuations being smoothed.