Coherent Propagation Phenomena in Three-Level Raman and Ladder Systems.

Ashat M. Basharov

M. G. Benedict, A. M. Ermolaev, В. А. Малышев +2 more

This chapter introduces a three-level atomic model and discusses two other coherent atomic phenomena; namely, coherent Raman scattering and lasing without inversion. Lasing without inversion may take place in three-level resonant atomic systems and, like super-radiance, results from atomic coherence. Super-radiation is initiated by spontaneous fluctuations of the polarization in the medium. The semiclassical method is a powerful tool that is useful for the treatment of propagation effects in super-radiance as well as in such coherent emission processes as self-induced transparency, photon echo and others. The use of the Maxwell—Bloch equations allows one to consider these phenomena in elongated systems. Fortunately, the semiclassical approach is readily applicable to low-density systems that are to gases. However, one has to exercise greater care when applying it to coherent emission in solids. In high-density systems there is a strong mixing of the field and atomic states in the vicinity of resonance.

Cen Jing-sheng

An investigation into lasing without inversion in a Ladder-type three-level atomic system was conducted.With the exhibiting condition of lasing without inversion,the effects of the incoherent pumping and spontaneously generated coherence(SGC) have been studied in detail.The investigation shows that SGC can decrease the phenomena of lasing without inversion(LWI).However,the incoherent pumping can strengthen it.

N. Tan-No, Tsukasa Shirahata, Kenichi Yokoto +1 more

Dingan Han, Yaguang Zeng, Weicheng Chen +2 more

The effects of spontaneously generated coherence (SGC) on the propagation of a weak probe pulse are investigated in a ladder-type atomic system. Due to SGC, the properties of the dispersion and the absorption of a three-level ladder-type system are changed greatly. With proper parameters, the system can produce normal and anomalous dispersion regions in the gain region. The effects of the incoherent pumping and the relative phase on the group velocity are also studied. They all can be used as switches to manipulate the group velocity of the weak probe field from gain-assisted sub- to superluminance.

Cyrus D. Cantrell, Frank Rebentrost, W. H. Louisell +1 more