Abstract: The present invention pertains to a unipolar quantum cascade laser consisting of several semiconductor multilayer structures (C) that are layered behind one another between two electrodes in a periodic sequence such that an active area (A) and a transitional or injection area (B) respectively alternate. The active areas (A) respectively have at least one upper and one lower energy level for electrons, between which electron transitions (T) emitting light take place. The transitional or injection areas (B) are realized in such a way that they allow the electron transport from the lower energy level of the preceding active area referred to the transport direction into the upper energy level of the following active area referred to the transport direction.

Abstract: The present invention pertains to a unipolar quantum cascade laser consisting of several semiconductor multilayer structures (C) that are layered behind one another between two electrodes in a periodic sequence such that an active area (A) and a transitional or injection area (B) respectively alternate. The active areas (A) respectively have at least one upper and one lower energy level for electrons, between which electron transitions (T) emitting light take place. The transitional or injection areas (B) are realized in such a way that they allow the electron transport from the lower energy level of the preceding active area referred to the transport direction into the upper energy level of the following active area referred to the transport direction.

Abstract: The invention relates to an unipolar quantum cascade laser comprising a plurality of adjacent semiconductor multilayer structures arranged in a periodic sequence through which an electron flow can be generated by providing at least two contact points, each of the multilayer structures having an optically active area comprising at least one quantum film structure in which there is at least one upper energy level and one lower energy level for the electrons, between which said levels light emitting electron transitions occur, as well as having a transition area comprising a plurality of semiconductor layers through which electrons from the lower energy level of said optically active area pass into the upper energy level of an optically active area of an adjacent semiconductor multilayer structure, which is directly adjacent to the transition area in the direction of electron transport, wherein the electron transitions and the electron transport occur solely in the conduction band of the semiconductor multilayer