The relationship between the reflectivity characteristic of a DBR
layer(s), in which an InP layer and an InGaAlAs layer are laminated
alternatively, and the optical absorption characteristic of the InGaAlAs
layer, is a trade-off in a vertical cavity surface emitting laser on an
InP substrate. The present invention applies a semiconductor DBR
layer(s), in which an InP layer and an InGaAlAs-MQW (multi-quantum-wells)
layer are laminated alternatively, in order to dissolve the above
trade-off. The InGaAlAs-MQW layer is composed of InGaAlAs-wells and
barriers. The InP layer is doped uniformly and the InGaAlAs-MQW layer has
a structure in which at least a part thereof is doped.