Fig. 1. Epitaxy design of the CQWs structure and schematic of the asymmetric Ge/SiGe CQW

Fig. 2. Wave functions at $\Gamma$ point of the asymmetric Ge/SiGe CQW under different electric fields. (a) E = 0 kV/cm; (b) E = 10 kV/cm; (c) E = 20 kV/cm; (d) E = 30 kV/cm; (e) E = 40 kV/cm; (f) E = 50 kV/cm

Fig. 3. Energy dispersion near $\Gamma$ point of the asymmetric Ge/SiGe CQW

Fig. 4. Transition energy at $\Gamma$ point of the asymmetric Ge/SiGe CQW under different electric fields

Fig. 5. Absorption spectrum of the asymmetric Ge/SiGe CQW under different electric fields for (a) TE and (b) TM polarization

Fig. 6. Absorption spectrum of the Ge/SiGe uncouple quantum wells under different electric fields for (a) TE and (b) TM polarization