A semiconductor laser device comprises an active layer of a refractive index n.sub.1, first and second inner cladding layers of a refractive index n.sub.2 and a bandgap energy greater than that of the active layer provided on the both sides of the active layer to form a double heterostructure, and fist...http://www.google.de/patents/US4941146?utm_source=gb-gplus-sharePatent US4941146 - Semiconductor laser device
