Heterostructure semiconductor laser diode

In a heterostructure semiconductor laser diode having a layer sequence formed on a substrate of one conductivity type (1), with the sequence including a laser-active zone (3) disposed between upper and lower enclosing layers (2, 4) of respectively opposite conductivity types, an additional layer (5) of the same conductivity type as the substrate (1) disposed on said upper enclosing layer on the side of the layer sequence facing away from the substrate, and a cover layer of the same conductivity type as the substrate disposed on said additional layer, and with said cover layer (6) including an oppositely doped diffused semiconductor region (13) which, in a strip-shaped zone extending perpendicularly to the exit surface of the laser radiation (18) in the area of the plane of symmetry (14) of the layer sequence and below a v-groove-shaped recess (16) formed in said cover layer, penetrates said additional layer (5) and extends into the said upper enclosing layer (4) located thereunder, whereby current flowing in the forward direction of the semiconductor laser diode is confined to a narrow, stripe-shaped area (15) of the laser-active layer (3);

• the improvement wherein:
• said oppositely doped semiconductor region extends into said upper layer but does not penetrate said active layer;
• the portion of said narrow, stripe-shaped area of the laser-active zone (3) which is beneath said v-groove shaped recess, and hence relevant to the amplification is significantly shorter in its length-wise dimensions than the resonator length (9) of the semiconductor laser diode by the laser-active layer (3) extending, in a small area (10) of the resonator length (9) immediately in front of the two mirrors (11, 12) of the semiconductor laser diode, at an incline to the main plane of the laser-active layer (3) and by the v-groove-shaped recess (16) being symmetrically shortened by the amount of this small area (10) in relation to the resonator length (9).