Abstract: It is provided a transistor vertical-cavity surface-emitting laser, T-VCSEL comprising: a collector section (13) comprising a bottom substrate (11) and a base contacting layer (172), defining the collector region, an emitter section (14) and a base section (16), arranged between the emitter section (14) and the collector section (13), and comprising a collector contacting layer (171) and a light emitting active layer (17), arranged between layers (15, 15?) of a base material. The emitter section (14) comprises a current confining blocking layer (110) that comprises a first material layer (112), having a first type of doping and comprising a current confining means (111, 211) and a second material layer (19), defining the emitter region, having a second type of doping and being provided on the base side of the material layer (112).

Abstract: A bottom emitting VCSEL where the light emitted can be monitored without obstruction. No additional mountings are required, such as a header, to monitor output, which mountings are necessary in prior art arrangements.

Abstract: An optical emission device includes a semiconductor with conduction and valence bands and a plurality of quantum wells formed in the conduction and valence bands in a multiple quantum well active region such that recombination of holes and electrons between said quantum wells results in the emission of light. At least some of the quantum wells have different characteristic emission frequencies to broaden the gain spectrum of the emitted light.