We investigated the effect of atomic dipole relaxation on temporal cloaking in a four-level N-type atomic system. Due to dipole relaxation rates, significant variation in the group index and in the advance/delay time of the probe pulse is noted. Temporal gaps of the order of nanoseconds are opened. Furthermore, multiple temporal gaps are created in a comparatively narrow probe pulse, whose quality is modified due to the width of the probe pulse and with the dipole relaxation rates. The results of this article will play a vital role in secure transmission and storage of information.

We investigate the possibility of creating spectral hole burning in surface plasmon polaritons (SPPs) at the interface of sodium vapor and gold media. The spectral holes are measured at specific parameters, phases and directions of the control fields. The direction and phase of the control field affect the creation of spectral hole burning in SPPs the most. The pulse shape in the spectral burning hole region is uniform and undistorted due to the cancellation of nonlinear Doppler broadening and large group velocity dispersion. The behavior of SPPs pulse in the spectral hole region is that of solitons, which arise due to cancellation of large positive dispersion for phase shift with nonlinear effect.. The results may have potential applications in nano-photonics, plasmonsters, photovoltaic devices, cloaking and sensing technology.

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