Fig. 1. Energy-level structure of an N-type four-level asymmetric double quantum well

Fig. 2. Linear absorption coefficient K0i as a function of the detuning Δp. (a) The second control field Ωc is turned off; (b) only the second control field Ωc is turned on; (c) both control fields are turned on

Fig. 3. Stability analysis of optical soliton considering low-order effect

Fig. 4. Stability analysis of optical soliton with high-order effects

Fig. 5. Storage and retrieval of control field. (a) Storage and retrieval of a weak pulse; (b) storage and retrieval of a soliton pulse; (c) storage and retrieval of a strong pulse

Fig. 6. Amplitude of storage and retrieval of optical soliton as a function of the second (Ωc) and both control fields. (a) The second control field; (b) both control fields