Quantum cascade lasers with blocking barriers in the active regions

Summary form only given. We report on a new design of GaInAs-AlInAs quantum cascade lasers (QCLs) improving the concept of Bragg reflectors by incorporating "blocking barriers" into the active regions. These barriers significantly enhance the confinement of electrons in the initial state of the laser transition by selectively blocking direct tunneling through the exit barrier (reducing the tunneling probability by a factor of 2). The high tunneling probability of electrons in the final state into the injector\´s miniband is maintained by reducing the total width of the exit barrier appropriately.