Patent ID: 6940883

Claim:
A laser diode for outputting light of a single spatial high order mode, the laser diode comprising: a substrate layer, a cladding layer, a light propagating layer located between the substrate layer and the cladding layer, and a gain means comprising at least one quantum well provided in the light propagating layer for defining a wave guiding region therein, a means being provided in one of the layers adjacent the light propagating layer for reducing the refractive index of the defined wave guiding region to be lower than the refractive index of an adjacent region in the light propagating layer in order that light of the highest order single spatial mode is propagated in the defined wave guiding region, so that when the defined wave guiding region is pumped the intensity of the light of the highest order single spatial mode is amplified above light of other lower order modes propagated in the light propagating layer.