Optical nonlinearity and atomic coherences

Xiuwen Xia, Xinqin Zhang, Jingping Xu +2 more

Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perfect absorber (CPA) beyond the linear regime. As nanowire-based system is a more competitive candidate for full-optical device, we introduce a nonlinear CPA in the single two-level atom–nanowires coupling system in this work. Nonlinear input–output relations are derived analytically, and three contributions of atomic saturation nonlinearity are explicit. The consociation of optical nonlinearity and destructive interference makes it feasible to fabricate a nonlinear monoatomic CPA. Our results also indicate that a nonlinear system may work linearly even when the incoming lights are not weak any more. Our findings show promising applications in full-optical devices.

С. А. Бахрамов

U. Rathea, Michael Fleischhauer, Marlan O. Scully

Systems with atomic coherence can have interesting optical properties, such as non-absorbing resonances or an index of refraction at a frequency of vanishing absorption many orders of magnitude larger than is otherwise possible. This chapter shows that phaseonium can display a large nonlinear Kerr-effect near the atomic resonance while retaining complete transparency. Near resonance nonlinearities are usually accompanied by a large absorption of the medium. A three-level atom is initially prepared in a coherent superposition of the two lower levels. This can be achieved for example by a coherent pulse excitation. The Kerr-coefficient is defined as the coefficient of the first nonlinear correction to the index of refraction.

Kh. V. Nerkararyan

Xiuwen Xia, Xinqin Zhang, Jingping Xu +2 more

We consider in this paper the input-output properties of an atom-nanowire coupling system which is composed of two individual terminated metal nanowaveguides and a two-level optical emitter. In detail, four aspects of the input-output properties are studied. First, we discuss in particular the coherent perfect absorber in the linear excitation regime and give the condition to realize it. Second, the transmittivity of the atom-nanowire system in the nonlinear regime is calculated, and a Rabi-like splitting associated with optical nonlinearity is found. Such a result is much different from the Rabi splitting in the atom-cavity system in the low excitation limit. Third, we find that the cooperation of optical nonlinearity and spatial asymmetry can generate optical nonreciprocity. Finally, a negative differential transmittivity is achieved with appropriate parameters. Our findings show promising applications in the full-optical device.

R.W. Smith