Fig. 1. The cascade three-level system of ⁸⁵Rb and the level diagram of the dressed states

Fig. 2. Experimental scheme

Fig. 3. Self-dressed FWM signal under different couplinglight detuning

Fig. 4. The AT splitting of FWM lines versus the coupling detuning deduced from Fig.3 and measured AT splitting of FWM lines by varying the coupling power P2' from 2.5 mW to 6.5 mW

Fig. 5. Calculated contribution of the residual Doppler shift to the real and the imaginary parts of σ10(3) and the real and the imaginary parts of σ10(3) versus Δp

Fig. 6. The AT splitting of FWM lines versus the average coupling Doppler detuning Δ2D and incoherent parameter p.（a） Δ2D；（b） p