THE EFFECT OF PHASE FLUCTUATION ON ELECTROMAGNETICALLY INDUCED TRANSPARENCY, INVERSIONLESS LASING AND REFRACTIVE-INDEX ENHANCEMENT IN A LAMBDA-SYSTEM

The steady-state behaviour for a Lambda-type, three-level atomic syste m has been analysed by taking into account the effect of the phase flu ctuation. It is shown that, for a monochromatic driving field, even if the probe field is in resonance with the corresponding atomic transit ion, a large refraction index can still be generated; for a finite lin ewidth of the driving field, inversionless lasing and index enhancemen t tends to disappear. Furthermore, the linewidth prevents the transpar ency of the medium.