Eur. Phys. J. D 13, 401-413 (2001)
https://doi.org/10.1007/s100530170259

Spectral linewidth of inversionless and Raman lasers in V-type three-level systems

Department of Physics, Huazhong Normal University, Wuhan 430079, P.R. China

Corresponding author: ^a xmhu@phy.ccnu.edu.cn

Received: 25 October 1999
Revised: 10 March 2000
Published online: 15 March 2001

Abstract

A theoretical analysis of the spectral linewidth of V-type inversionless and Raman lasers is presented. First, we examine the effects of the atomic coherence between dressed states and the Autler-Townes splitting on the linewidth. It is demonstrated that near above threshold, the V inversionless laser has a narrower linewidth than that of the two-level laser. Instead of the dressed coherence, it is the Autler-Townes splitting that is responsible for the linewidth reduction though the dressed coherence determines the laser gain. Next, we explore the effects of the generated laser intensity on the linewidth. It is shown that the linewidths of the V inversionless and Raman lasers follow the usual 1/I decrease for smaller laser intensity I, but a slower decrease than 1/I for larger laser intensity. For the V Raman laser, even more surprisingly, with the laser intensity increasing, the linewidth appreciably increases as well. As a result, well above threshold, the V inversionless and Raman lasers may have a larger linewidth than that of the two-level laser. Finally, a comparison is made between the V lasers and the lasers. It is found that the linewidth of the inversionless laser shows a fast decay under optimum conditions.