Fig. 1. Absorption peaks of various gases^[8]

Fig. 2. Energy band diagram of quantum well cascade laser^[39]

Fig. 3. Conduction band and energy level of 3 μm QCL^[59]

Fig. 4. Energy band diagram of active region of early time ICL^[64]

Fig. 5. Energy band diagram of active region of ICL^[102]

Fig. 6. Current-output power curves for the ICL of NRL^[115]

Fig. 7. Emission spectra for the ICL of NRL^[115]

Fig. 8. Full structure diagram of the interband cascade laser^[61]

Fig. 9. Energy band diagram of interband cascade laser with transition layer^[109]

Fig. 10. Energy band diagram of cascade region of ICL^[61]

Fig. 11. Energy gap, energy band edge, and lattice constant of InAs, GaSb, and AlSb^[120]

Fig. 12. Relationship between threshold current and temperature for short injection zone design^[109]

Fig. 13. Energy band and carrier distributions of rebalancing of carriers^[102]. (a) Electron injection zone with medium doping concentration of 4×10¹⁷ cm^-3; (b) electron injection zone with heavy doping concentration of 5×10¹⁸ cm^-3

Fig. 14. Refractive index and optical TE mode distribution of SCL at 800 nm in 7 cascade regions^[115]

Fig. 15. Optical confinement factor for active region, waveguide cladding, separate confinement layers, and transition layer^[115]

Fig. 16. 10 μm×10 μm atomic force microscope photo of interband cascade laser^[61]

Fig. 17. HR-XRD[004] diffraction curve of ICL^[61]

Fig. 18. SEM sidewall topography of an interband cascade laser with seven cascade cycles. (a) Methane-based etching;(b) BCl₃-based etching^[126]