The classical concept of quantum-cascade lasers consists of alternating active sections and and injector regions. In the active sections the photons are generated, while a bridging miniband in the injector regions enables the transfer of the electrons from one active section into the next. The main disadvantage of these structures is the lengthening of the active stage with optically passive material. Within this work, a new concept of quantum-cascade lasers without injector regions has been investigated. A so-called 5-level concept was developed, which ensures the transfer of electrons and reduces the thermal backfilling of the lower laser state. Injectorless qc lasers have been demonstrated, which outmatch all conventional quantum-cascade lasers realized so far, regarding the threshold current density. Furthermore, the available wavelength region for injectorless qc lasers was extended from 10 µm down to 4.65 µm.
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The classical concept of quantum-cascade lasers consists of alternating active sections and and injector regions. In the active sections the photons are generated, while a bridging miniband in the injector regions enables the transfer of the electrons from one active section into the next. The main disadvantage of these structures is the lengthening of the active stage with optically passive material. Within this work, a new concept of quantum-cascade lasers without injector regions has been inv...
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