| An infrared light emitter includes a substrate, a first light-emitting layer, a blocking layer, and a second light-emitting layer.  The second light-emitting layer is disposed on the substrate, the blocking layer is disposed on the second light-emitting layer, and the first light-emitting layer is disposed on the blocking layer.  The first light-emitting layer, the blocking, and the second light-emitting layer form a P-N-P junction or an N-P-N junction.  The first light-emitting layer and the blocking layer form a first electroluminescent unit, and the blocking layer and the second light-emitting layer form a second electroluminescent unit.  The first electroluminescent unit and the second electroluminescent unit build two back-to-back bipolar junctions. |