Compression of electromagnetic radiation pulses in media with strong spatial dispersion

Gennady A. Lyakhov, Vladimir Makarov

Peter Jänes, Jonas Tidström, Lars Thylen

Delay bandwidth products (DBPs) and physical pulselengths obtainable in media exhibiting electromagnetically induced transparency (EIT) are analyzed. The study is performed in stationary media as well as for dynamic storing of light pulses in such media. In the latter case, the dispersion inherent in storage and readout of the pulses is analyzed. It is shown that absorption and the group velocity dispersion (GVD) are limiting factors. Analytical expressions for the minimum compressed pulselength and DBP are derived, and these expressions show good agreement with simulations of pulse propagation in EIT media.

Yu. M. Zhidko

Yu. I. Heller

The influence of spectral interference of various nature on the effects of radiation drag is studied using as examples electromagnetically induced transparency in pure discrete atomic transitions and the transparency windows of autoionization resonances of gaseous media. The analysis is performed using the Maxwell equations and taking into account the equivalence of the corresponding spatial dispersion of a substance and the optical effects caused by uniform motion. The realization conditions of the drag coefficients in the Lorentz and Laub forms are found from the exact dispersion equations obtained. A direct relation between the monochromatic radiation drag coefficient and the decrease in the pulsed radiation group velocity due to high frequency dispersion of the resonant refractive index is found. The known experimental data on ultraslow light pulses indicate the possibility of interference enhancement of the light drag effect by a factor of 10 6 -10 7 .

Yury V. Kistenev, Alexander V. Shapovalov

Lipsa Nanda, Harshawardhan Wanare, S. Anantha Ramakrishna

We use the time moments of the Poynting vector associated with an electromagnetic pulse to characterize the traversal times and temporal pulse widths as the pulse propagates in highly dispersive media. The behaviour of these quantities with the propagation distance is analysed in three canonical cases: Lorentz absorptive medium, a Raman gain doublet amplifying medium and a medium exhibiting electromagnetically induced transparency. We find that superluminal pulse propagation in the first two cases with anomalous dispersion is usually accompanied by pulse compression and eventually the pulse becomes subluminal with increasing distance of propagation. In a medium with electromagnetically induced transparency with large normal dispersion, we identify a range of frequencies for which the pulse undergoes minimal temporal expansion while propagating with ultra-slow speed.