Semiconductor laser with multiple quantum well active layer including modulation-doped barrier layers

Abstract

In a semiconductor laser which is modulation-doped in an active layer having a multiple quantum well structure, emission efficiency and modulation-band are improved. A semiconductor laser has an active layer between a p-type cladding layer and an n-type cladding layer. The active layer has multiple quantum wells with a plurality of barrier layers and well layers, and at least one barrier layer is p-type modulation-doped. More specifically, quantity of p-type modulation-doping of a barrier layer close to the p-cladding layer is smaller than of a barrier layer close to the n-cladding layer. Therefore, differential gain and high-speed response can be improved while suppressing nonluminous recombination. Since the concentration of holes is high in a well layer distant from the p-type cladding layer, the nonuniformity of carrier concentration can also be reduced.