Semiconductor laser with active layer having a radiation emitting active region therein which extends through and is bounded by a current limiting blocking layer

Claim 1

A semiconductor laser comprising a semiconductor substrate having a layer structure disposed thereon, such layer structure comprising: a first passive layer of a first conductivity type; a second passive layer of a second opposite conductivity type; an active layer of said first conductivity type interposed between said passive layers and forming a pn junction with said second passive layer, an area of said active layer defining an active region therein; a pair of reflectors forming a resonant cavity for electromagnetic radiation, said cavity being positioned so that said active region is included therein; and a current-limiting blocking layer of said secon conductivity type laterally bounding said active region of said active layer; said pn junction producing, at a sufficiently high forward current, coherent electromagnetic radiation emitted from said active region in a direction at right angles to said active layer and which is reflected by said reflectors; said first and second passive layers and said blocking layer each having a larger band gap and a smaller refractive index than said active layer for the radiation emitted by said active region; characterized in that: said blocking layer is disposed between said active layer and said first passive layer; and said active region of said active layer has a thickness greater than the remainder of said active layer and extends through said blocking layer at least as far as said first passive layer.