Ultra—narrow electromagnetically induced transparency and inversionless gain in a ladder—four—level system

Guiyin Zhang, Weiwei Shi, Yi-dong Jin +1 more

Sheng-Xian Xiao, Tao Wang

Alan V. Durrant

Li Yongfang, Sun Jian-feng, 陕西师范大学物理学与信息技术学院,西安〓710062

In this paper, we study the effects of Rabi frequencies and multi-path radiation on the electromagnetically induced transparency (EIT) and the inversionless gain in a ladder- four-level system driven by two-coherent fields- The Rabi frequencies of the field-driven transition from the upper level to middle levels play an important role for the realization of the ultra-narrow EIT and inversionless gain- Different excitation mechanism can change the position of the EIT- The action of the spontaneous alignment of the dipole moment is investigated- The explanation for the numerical results is presented using the theory of dressed state

Ljiljana Stevanović, Nikola Filipović, Vladan Pavlović

Zhiguo Wang, Cheng Li, Zhaoyang Zhang +4 more

We simultaneously compare the probe transmission, Four-Wave Mixing (FWM) and fluorescence signals with dressing effects in a four-level atomic system. The variation rules of three types of signals are exhibited by changing the frequency detuning and power of incident laser beams. The interplay between two ladder subsystems is investigated in the Y-type atomic system. In particular, the fluorescence signal with ultra-narrow linewidth is obtained due to being sheared twice by the electromagnetically induced transparency window. Such fluorescence with very high coherence and monochromaticity can be used for the quantum correlation and narrow linewidth laser.