Fig. 1. DNA and peptide quantum dot coupling system: a peptide quantum dot coupled to DNA molecules in the simultaneous presence of two optical fields. The energy level structure of the quantum dot dressed by the vibrational modes of DNA molecules is also shown.

Fig. 2. Optical dispersions and nonlinear absorptions (in units of Σ3 and Σ5 for χ(ωp−2ωs)eff(3) and χ(−3ωp+2ωs)eff(5), respectively) with pump beam on-resonance (Δp=0). (a) Third-order optical dispersion and nonlinear absorption as functions of probe-exciton detuning Δs in the case λ=0. (b) Third-order optical dispersion and nonlinear absorption as functions of probe-exciton detuning Δs in the case λ=2  GHz. (c) Fifth-order optical dispersion and nonlinear absorption as functions of probe-exciton detuning Δs in the case λ=0. (d) Fifth-order optical dispersion and nonlinear absorption as functions of probe-exciton detuning Δs in the case λ=2  GHz.

Fig. 3. ζ3 value caused by third-order nonlinearity with pump beam off-resonance. (a) ζ3 value as a function of probe-pump detuning in the case Δp=−ωD. (b) ζ3 value as a function of probe-pump detuning in the case Δp=1.25ωD. (c) Parametric process of point δ/ωD=−1 in Fig. 3(a), where ωsd=ωp−2ωD is the frequency of the sideband beam.

Fig. 4. ζ3 value by third-order nonlinearity with different Rabi frequency and exciton-pump detuning. (a) ζ3 value as a function of Rabi frequency in the case Δp=−ωD and δ=−ωD. (b) ζ3 value as a function of exciton-pump detuning Δp in the case δ=−ωD and Ωp=5  GHz.

Fig. 5. ζ5 value caused by fifth-order nonlinearity with exciton-pump detuning Δp=−ωD and different δ. (a) ζ5 value as a function of Rabi frequency in the case δ=−ωD. (b) ζ5 value as a function of Rabi frequency in the case δ=ωD.