Experimental and theoretical density-dependent absorption spectra in (GaInSb/InAs)/AlGaSb superlattice multiple quantum wells

A broadly tunable, ultrafast optical parametric oscillator is used to measure carrier-density-dependent absorption spectra in a 340-meV band gap (GaInSb/InAs)/AlGaSb superlattice multiple quantum well structure. Similar structures have been implemented recently as the active region in midinfrared diode lasers. The measured spectra are compared with calculated spectra computed using a semiempirical eight-band superlattice K⋅p model. The model provides good agreement with the experimentally observed spectral and density dependence of the absorption. These results provide confirmation that the model may be used for band structure engineering of optimized midinfrared laser active regions.