Controlling self-Kerr nonlinearity with an external magnetic field in a degenerate two-level inhomogeneously broadened medium

A fast laser pulse with a q-deformed hyperbolic function shape is investigated in a Multi-level atomic system. Therefore, we first derive the exact solution of the Bloch equations describing a two-level atom excited by a q-deformed laser pulse with dephasing and time-dependent detuning. Next, we analyze the dynamic of the atomic population inversion at resonance and off-resonance of a Rubidium 87 three-level atom driven by a classical weak field and a strong q-deformed control laser. Finally, in order to get a deeper insight of the probe field's absorption and dispersion properties, we investigate the coherence's dependence on the q-deformation. Our work demonstrates that, the dynamic of the atomic system can be fully controlled through the manipulation of the asymmetry scaling parameter q of the q-deformed hyperbolic laser wave-form. 

/pdf/analysis-of-a-q-deformed-hyperbolic-short-laser-pulse-in-a-f37pimk3.pdf

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

We proposed a simple model for generation of controllable ultraslow optical solitons of a weak probe laser light in a degenerated two-level atomic medium under electromagnetically induced transparency assisted by a magnetic field. It is shown that bright and dark optical solitons can be formed from a probe light with controllable ultraslow group velocities at a few m/s by tuning the strength of a coupling light and/or the magnetic field. In addition to the ultraslow velocity, the advantage of this model is to use a sole laser for delivering both pump and probe lights. Furthermore, one can switch between bright and dark solitons by reversing the direction of the magnetic field. Such controllable ultraslow solitons are interested in finding applications in optical communications and optical data processing.

/pdf/controllable-ultraslow-optical-solitons-in-a-degenerated-two-3wkr2akg3b.pdf

Controllable ultraslow optical solitons in a degenerated two-level atomic medium under EIT assisted by a magnetic field.

Controllable Kerr nonlinearity in a degenerate V-type inhomogeneously broadening atomic medium aided by a magnetic field

We study the all-optical switching of the weak probe field via a four-level atom system with the help of a microwave field and electromagnetically induced transparency effect. Here, the microwave field is used for coupling two-folded lower levels to which double dark resonances (DDRs) can arise. The atomic medium is switched from transparent to complete absorption under the DDRs. It is shown that the absorption spectrum, pulse propagations and all-optical switching dynamics of the probe field are dependent on the intensity of the microwave field, applied fields and probe detuning. Furthermore, the switching mode between the probe field and the microwave field can be antisynchronous or synchronous, depending on the probe detuning being adjusted to be equal to zero or ± $$\Omega _{{c}}$$
 , respectively. Our results possibly are helpful in actual tests to design all-optical switching and optical storage devices in optical communications and signal processing.

Microwave-assisted all-optical switching in a four-level atomic system

We propose a simple system for both optical switching and bistability based on degenerated two-level atoms placed in a ring cavity and an external magnetic field. The magnetic field splits a lower level into two separated levels, both of which are connected to an upper level by coupling and probe laser fields. Under an electromagnetically induced transparency regime, the system exhibits optical bistability and switching properties in which its thresholds and switching rate can be controlled by modulating intensity of the magnetic field or the coupling light field. Furthermore, the system can be controlled to work in varying frequency regimes by using a sole laser for both coupling and probe fields. Such a proposed scheme may be useful for realization of optical switches and storage devices.

Optical switching and bistability in a degenerated two-level atomic medium under an external magnetic field.

Optical bistability (OB) of an electromagnetically induced transparency (EIT) medium placed in a conventional unidirectional ring cavity is investigated numerically. The medium is excited by a coupling and probe laser lights via a five-level cascade scheme. It is shown that optical bistabe states with controllable switching threshold intensities and width establish simultaneously in three spectral regions corresponding to EIT windows. The current numerical result is compared to a previous analytical result showing influence of coherence terms neglected in the analytical model.

/pdf/controlling-optical-bistability-in-a-five-level-cascade-eit-5fonrs8q65.pdf

Luong Thi Yen Nga

Papers

Optical switching and bistability in a degenerated two-level atomic medium under an external magnetic field.

Controlling Optical Bistability in a Five-level Cascade EIT Medium