Arrangement of semiconductor diode lasers stacked one above another comprising: - a substrate, on which a first diode laser is arranged; - a second diode laser arranged on the first diode laser; and - a contact layer arranged between the first diode laser and the second diode laser, wherein the contact layer comprises a first conductive layer of a first conduction type, a second conductive layer of a second conduction type, and wherein the contact layer either a) comprises an intermediate layer which is arranged between the first and second conductive layers (18, 20) and increases the tunnelling probability for charge carriers, wherein the intermediate layer is undoped or the intermediate layer is doped with the first conduction type but has a lower dopant concentration than the first conductive layer of the first conduction type, or b) comprises a first intermediate layer and a second intermediate layer, wherein the first and second intermediate layers (22, 23) are arranged between the first and second conductive layers (21, 24) and the first intermediate layer faces the first conductive layer and the second intermediate layer faces the second conductive layer, and wherein the first or the second intermediate layer (22, 23) has a thickness of between 4 and 12 nm. - a substrate, on which a first diode laser is arranged; - a second diode laser arranged on the first diode laser; and - a contact layer arranged between the first diode laser and the second diode laser, wherein the contact layer comprises a first conductive layer of a first conduction type, a second conductive layer of a second conduction type, and wherein the contact layer either a) comprises an intermediate layer which is arranged between the first and second conductive layers (18, 20) and increases the tunnelling probability for charge carriers, wherein the intermediate layer is undoped or the intermediate layer is doped with the first conduction type but has a lower dopant concentration than the first conductive layer of the first conduction type, or b) comprises a first intermediate layer and a second intermediate layer, wherein the first and second intermediate layers (22, 23) are arranged between the first and second conductive layers (21, 24) and the first intermediate layer faces the first conductive layer and the second intermediate layer faces the second conductive layer, and wherein the first or the second intermediate layer (22, 23) has a thickness of between 4 and 12 nm. a) comprises an intermediate layer which is arranged between the first and second conductive layers (18, 20) and increases the tunnelling probability for charge carriers, wherein the intermediate layer is undoped or the intermediate layer is doped with the first conduction type but has a lower dopant concentration than the first conductive layer of the first conduction type, or b) comprises a first intermediate layer and a second intermediate layer, wherein the first and second intermediate layers (22, 23) are arranged between the first and second conductive layers (21, 24) and the first intermediate layer faces the first conductive layer and the second intermediate layer faces the second conductive layer, and wherein the first or the second intermediate layer (22, 23) has a thickness of between 4 and 12 nm.