Laser and method of making same

Claim 1

IN A DOUBLE HETEROSTRUCTURE LASER DIODE INCLUDING A SEMICONDUCTOR BODY HAVING A LIGHT EMITTING ACTIVE LAYER, A HIGHLY DOPED FIRST LAYER OF A CONDUCTIVITY TYPE OVERLYING ONE MAJOR SURFACE OF SAID ACTIVE LAYER, A SECOND LAYER OF SAID FIRST CONDUCTIVITY TYPE OVERLYING SAID FIRST, A THIRD HIGHLY DOPED LAYER OF THE OPOSITE CONDUCTIVITY TYPE OVERLYING THE OPPOSITE MAJOR SURFACE OF SAID ACTIVE LAYER AND A FOURTH LAYER OF SAID OPPOSITE CONDUCTIVITY TYPE OVERLYING SAID THIRD LAYER, SAID FIRST AND THIRD LAYERS BEING FORMED OF A CRYSTAL WHOSE BAND SPACING BETWEEN THE VALANCE BAND AND THE CONDUCTIVE BAND IS GREATER THAN THAT OF THE CRYSTAL WHICH FORMS SAID ACTIVE LAYER, THE IMPROVEMENT COMPRISING: FIRST MEANS EXTENDING INTO SAID SEMICONDUCTOR BODY FROM ONE MAJOR SURFACE THEREOF THROUGH SAID SECOND LAYER AND AT LEAST INTO SAID FIRST LAYER FOR CONFINING THE CURRENT FLOW THROUGH SAID FIRST AND SECOND LAYERS TO A NARROW PATH AND FOR BLOCKING CURRENT FLOW THROUGH LATERALLY EXTENDING PORTIONS OF SAID FIRST AND SECOND LAYERS; AND FURTHER MEANS FOR LIMITING THE CURRENT FLOW IN SAID FOURTH LAYER TO A NARROW PATH WHICH IS ALIGNED WITH THE SAID NARROW PATH THROUGH SAID FIRST AND SECOND LAYERS, AND FURTHER MEANS COMPRISES SPACED APART SEMICONDUCTOR REGIONS OF SAID FIRST CONDUCTIVITY TYPE WITHIN SAID FOURTH LAYER AT THE INTERFACE OF SAID THIRD AND FOURTH LAYERS AND FORMING RESPECTIVE BARRIER LAYERS WITH SAID FOURTH LAYER, SAID NARROW PATH IN SAID FOURTH LAYER BEING BETWEEN SAID BARRIER LAYERS.