We discuss the electromagnetically induced transparency (EIT) phenomenon for a model in which a structured continuum is described by a so-called double Fano structure; instead of one autoionizing (AI) state, two such states are embedded in a flat continuum. Such a Fano structure is the upper level of a Λ-like three-level system and is coupled to two lower ones by an external laser field involving δ-correlated, Gaussian, Markov process (white noise), simulating realistic conditions of the experiment. For such a system we derived and solved a set of coupled stochastic integrodifferential equations in the stationary regime, obtaining exact formulas determining the electric susceptibility of the system. Dispersion and absorption spectra of the medium susceptibility were calculated and compared with those already discussed in the literature. We have shown that the presence of an additional AI level considerably changes the structure of transparency windows and how noisy excitation influences the EIT processes.
We discuss the electromagnetically induced transparency (EIT) phenomenon for a model in which a structured continuum is described by a so-called double Fano structure; instead of one autoionizing (AI) state, two such states are embedded in a flat continuum. Such a Fano structure is the upper level of a Λ-like three-level system and is coupled to two lower ones by an external laser field involving δ-correlated, Gaussian, Markov process (white noise), simulating realistic conditions of the experiment. For such a system we derived and solved a set of coupled stochastic integrodifferential equations in the stationary regime, obtaining exact formulas determining the electric susceptibility of the system. Dispersion and absorption spectra of the medium susceptibility were calculated and compared with those already discussed in the literature. We have shown that the presence of an additional AI level considerably changes the structure of transparency windows and how noisy excitation influences the EIT processes.
In this paper, electric susceptibility of a laser-dressed atomic medium is calculated for a model Λ-like system which includes two lower states and a structured continuum. It is assumed that the laser control field applied in the experiment of electromagnetically induced transparency can be decomposed into two parts: a deterministic (coherent) part and a randomly fluctuating chaotic component (white noise). The exact formulae determining the dispersion and absorption spectra of the medium susceptibility are derived by solving a set of coupled stochastic integro-differential equations. The results show that the position and width of the transparency window change dramatically in comparison with the case when the noise of the control laser is absent.
A Λ-like model of atomic levels involving two auto-ionizing states is considered. The levels are irradiated by two external electromagnetic fields, a strong driving and a weak probing ones. The analytical formula for medium susceptibility shows an additional electromagnetically induced transparency window caused by the second auto-ionizing level. Characteristics of both transparency windows are analyzed depending on parameters of auto-ionizing levels and the external driving field. Manipulation of these characteristics seems to be very effective because of their large sensitivity with respect to the parameters involved in the problem. This manipulation becomes even more feasible when considered model is implemented in so-called laser-induced continuum structure.
We discuss the propagation of a short laser pulse in an autoionizing medium with double Fano structure. By solving the coupled equations for atoms and fields simultaneously, we can consider the influence of double Fano structure on the pulse laser in the transmission process. Full Text: PDF References A. Raczynski, M. Rzepecka, J. Zaremba, and S. Zielinska-Kaniasty, Electromagnetically induced transparency and light slowdown for Λ-like systems with a structured continuum, Opt. Commun. 266, 552 (2006). CrossRef T. Bui Dinh, W. Leonski, V. Cao Long and J. Perina Jr, Electromagnetically induced transparency for a double Fano-profile system, Eur. Phys. J. D, 68 (2014) CrossRef T. Bui Dinh, W. Leonski, V. Cao Long and J. Perina Jr, Electromagnetically induced transparency in systems with degenerate autoionizing levels in Λ-configuration, Optica Applicata 43, 471 (2013). CrossRef Cao Long Van, Structured continuum in various optical phenomena, in Physics and applications I: Quantum Optics Ed. Wieslaw Leonski, University of Zielona Gora Press, p.195 (2012). DirectLink M. Shapiro, Electromagnetically induced transparency with structured multicontinua, Phys.Rev.A 75, 013424 (2007). CrossRef E. Paspalakis, P.L. Knight, Population transfer via an autoionizing state with temporally delayed chirped laser pulses, J. Phys. B 31, 2753 (1998). CrossRef S.Y. Zhu and E.E. Fill, Nonlinear theory of lasers without inversion with two upper lasing levels, Phys. Rev. A 42, 5684 (1990). CrossRef S. E. Harris, Lasers without inversion: Interference of lifetime-broadened resonances, Phys. Rev. A 62, 1033 (1989). CrossRef E. Paspalakis, N. J. Kylstra, and P. L. Knight, Propagation dynamics in an autoionization medium, Phys. Rev. A 60, 642 (1999). CrossRef W. Leonski, R. Tanaś and S. Kielich, Laser-induced autoionization from a double Fano system, J. Opt. Am. B 4, 72 (1987). CrossRef
We discuss a Λ-like model of atomic levels involving two autoionizing (AI) states of the same energy. The system is irradiated by two external electromagnetic fields (strong -- driving and weak -- probing ones). For such a system containing degenerate AI levels we derive the analytical formula describing the medium susceptibility. We show that the presence of the second AI level lead to the additional electromagnetically induced transparency (EIT) window appearance. We show that the characteristic of this window can be manipulated by changes of the parameters describing the interactions of AI levels with other ones. This is a new mechanism which leads to additional transparency windows in EIT model, that differs from the mechanism, where a bigger number of Zeeman sublevels is taken into account.
We discuss the propagation of a short laser pulse in an autoionizing medium with double Fano structure. By solving the coupled equations for atoms and fields simultaneously, we can consider the influence of double Fano structure on the pulse laser in the transmission process. Full Text: PDF References A. Raczyński, M. Rzepecka, J. Zaremba, and S. Zielińska-Kaniasty, "Electromagnetically induced transparency and light slowdown for Λ-like systems with a structured continuum", Opt. Commun. 266, 552 (2006). CrossRef T. Bui Dinh, W. Leoński, V. Cao Long and J. Perina Jr, "Electromagnetically induced transparency for a double Fano-profile system", Eur. Phys. J. D, 68 (2014) CrossRef T. Bui Dinh, W. Leoński, V. Cao Long and J. Perina Jr, "Electromagnetically induced transparency in systems with degenerate autoionizing levels in Λ-configuration", Optica Applicata 43, 471 (2013). CrossRef Cao Long Van, Structured continuum in various optical phenomena, in Physics and applications I: Quantum Optics" Ed. Wiesław Leoński, University of Zielona Góra Press, p.195 (2012). DirectLink M. Shapiro, "Electromagnetically induced transparency with structured multicontinua", Phys.Rev.A 75, 013424 (2007). CrossRef E. Paspalakis, P.L. Knight, "Population transfer via an autoionizing state with temporally delayed chirped laser pulses", J. Phys. B 31, 2753 (1998). CrossRef S.Y. Zhu and E.E. Fill, "Nonlinear theory of lasers without inversion with two upper lasing levels", Phys. Rev. A 42, 5684 (1990). CrossRef S. E. Harris, "Lasers without inversion: Interference of lifetime-broadened resonances", Phys. Rev. A 62, 1033 (1989). CrossRef E. Paspalakis, N. J. Kylstra, and P. L. Knight, "Propagation dynamics in an autoionization medium", Phys. Rev. A 60, 642 (1999). CrossRef W. Leoński, R. Tanaś and S. Kielich, "Laser-induced autoionization from a double Fano system", J. Opt. Am. B 4, 72 (1987). CrossRef
We report the observation of tunneling induced transparency in asymmetric double quantum well structures. Resonant tunneling through a thin barrier is used to coherently couple the two upper states in a three level system of electronic subbands in a GaAs/AlGaAs structure. This creates Fano-type interferences for the collective intersubband excitations in the absorption from the ground state, analogous to electromagnetically induced transparency (EIT) in atomic systems. We observe a 50% reduction in absorption between the subband resonances which can be explained by taking into account the coherent coupling of the upper states. We analyze the bias dependent absorption spectra and determine the relevant lifetime broadening and dephasing rates for the transitions.