Controllable refractive index in a four-level left-handed medium using pulse shaping

Abstract

In this paper we control the negative refractive index of a four-level left-handed medium by applying different waveforms to excite the atomic system. The control field is a few-cycle strong pulse described by a double exponential function, and its modified forms, a Gaussian field, and a tan-hyperbolic pulse. The considered four-level system was fully analyzed in terms of the density matrix formalism under the rotating wave approximation, and the refractive index for various control fields was obtained. Hence, under specific conditions, the tunneling, and the modulation of the negative refractive index are achieved for various shaped waveforms. Such strong-shaped laser pulses open the way to fully control the system.

Negative refractive index enhancement with zero absorption in a concentric chiral metal-atomic nanoshell

“…Intuitively, the permeability order for a natural medium, as studied by Thommen and Mandel, can be increased by using the coupled electric transition to induce magnetic moments in the medium [27]. Moreover, numerous atomic schemes [28][29][30][31] have been investigated for electromagnetic-induced chirality [28], light drag in left handed dense atomic medium [32], Kerr effect in left handed material [33] and negative refraction with suppressed absorption [31,[34][35][36][37] using the quantum coherence phenomenon of electromagnetic induced transparency [28] and gain [38] of a probe field.…”

Analysis of a q-deformed hyperbolic short laser pulse in a multi-level atomic system

“…Recently, Yudi et al, used various delayed picosecond pulses to generate arbitrarily shaped optical waveforms with a bandwidth of 30 GHz and a duration of 100 ps, resulting in “super-resolved” spectroscopic signals, which could open up intriguing possibilities in quantum optics based on fast laser cooling and atom interferometry with mode-locked lasers 24 . In addition, theoretical investigation of various waveforms in a four-level atomic system allowed the control of the negative refraction in a Rb 87 atomic media 25 . Besides, the introduction of a complex cosine amplitude combined with a phase jump enabled the atomic population inversion in a V-type three level system, in contrast with the standard case where the laser beam is a constant or a gaussian field 26 .…”