Electromagnetically Induced Transparency in a Double-Lambda System

Arno Huss, Roland Lammegger, Laurentius Windholz

Arno Huss, Eugeny Korsunsky, Laurentius Windholz

It is experimentally demonstrated that the effect of electromagnetically induced transparency (EIT) can be controlled through the radiation phases. Corresponding investigations are performed by exciting a sodium atomic vapour by four-frequency laser radiation in a double-Λ configuration. In such a system the nonabsorbing (dark) state, responsible for EIT, is created only for particular values of the relative radiation phase. This phase dependency is confirmed using three different methods of phase control. Additionally, the relative phase is set at defined values in order to adjust the medium to a fixed transmission behaviour.

Zhengyang Bai, Chao Hang, Guoxiang Huang

A. Kasapi, G. Y. Yin, Manoj Kumar Jain +2 more

Yi‐Hsin Chen, Pin-Ju Tsai, Ite A. Yu +2 more

We theoretically investigate a double-Λ electromagnetically induced transparency (EIT) system. The property of the double-Λ medium with a closed-loop configuration depends on the relative phase of the applied laser fields. This phase-dependent mechanism differentiates the double-Λ medium from the conventional Kerr-based nonlinear medium, e.g., EIT-based nonlinear medium discussed by Harris and Hau [Phys. Rev. Lett. 82, 4611 (1999)], which depends only on the intensities of the applied laser fields. Steady-state analytical solutions for the phase-dependent system are obtained by solving the Maxwell-Bloch equations. In addition, we discuss efficient all-optical phase modulation and coherent light amplification based on the proposed double-Λ EIT scheme.

Jelena Dimitrijević, D. Arsenović

We study a double-Λ atomic scheme that interacts with four laser light beams so that a closed loop of radiation-induced transitions is formed. When specific relations for field phases, frequencies and amplitudes are satisfied, coherent superpositions (the so-called ‘dark states’) can be formed in a double-Λ, which leads to the well-known effect of electromagnetically induced transparency (EIT). If the interaction scheme in a double-Λ system is such that a closed loop is formed, the relative phase of the laser light fields becomes very important. We analyze here the effect of the lasers' relative phase on the EIT in double-Λ configuration of levels. The theoretical study of interactions of lasers with a double-Λ atomic scheme is commonly conducted by solving the optical Bloch equations (OBEs). We use here a perturbative method for solving OBEs, where the interaction of lasers with double-Λ is considered a perturbation. An advantage of the perturbative method is that it generally produces simpler solutions, and analytical expressions can be obtained. We present analytical expressions for the lower-order corrections of the EIT signal. Our results show that the EIT by the perturbative method can be approximated by the sum of products of complex Lorentzians. Through these expressions, we see in what way the relative phase affects the overall EIT profile.