ABSTRACT
Intervalence band absorption coefficient has been calculated for long wavelength laser material on the base of InAs. Calculations have been fulfilled with the four band Kane model. Analytical expressions are obtained for the transitions between heavy and light hole bands and split-off band. It is shown that due to near coincidence of the band gap with the value of the spin-orbital splitting intervalence band absorption in these materials is much stronger than in the short wavelength lasers and can be comparable with the value of gain. Such absorption can heavily influence threshold current, differential gain and quantum efficiency of these lasers woridng in the 3–4 µm region.
