Figure 3
Energy band diagram. (a) Calculated conduction band diagrams of one period of the 30-stage QDCL active core under an electric field of 57 kV/cm using 1D model. The wavy curves represent the moduli squared of the wave functions of the relevant quantum states. The optical transition takes place between states 9 and 8. (b) Schematic illustration of electron energy (E) versus in-plane wave vector (Kin-plane) relation for a period of QDCL. The in-plane state distribution is hybrid-quantized or quantized because of 3D confinement. The upper broken lines denote the hybrid-quantized states, while the lower heavy dots stand for quantized states (dotted lines indicate quasi-continuous bands of the two-dimensional confinement). (c) Schematic sketch of the relevant energy levels in a QDCL.