  We have used an eight band model to investigate the electronic structures and
to calculate the optical matrix elements of InAs-GaSb broken gap semiconductor
heterostructures. The unusual hybridization of the conduction band states in
InAs layers with the valence band states in GaSb layers has been analyzed in
details. We have studied the dependence of optical matrix elements on the
degree of conduction-valence hybridization, the tuning of hybridization by
varying the width of the GaSb layers and/or InAs layers, and the sensitivity of
quantized levels to this tuning. Large spin-orbit splitting in energy bands has
been demonstrated. Our calculation can serve as a theoretical modeling for
infrared lasers based on broken gap quantum well heterostructures.
