Semiconductor laser device having a resonator of a particular length for reducing threshold current density

摘要

A semiconductor laser device includes a substrate and a laminated structure formed on a top face of the substrate. The laminated structure includes (a) first and second guide layers and (b) a quantum well structure of compound semiconductor interposed between the first and second guide layers. The quantum well structure serves as a resonator of the device and includes at least one quantum well layer and at least one barrier layer. The quantum well layer has a thickness Lz and the barrier layer has the energy gap larger than the energy gap of the quantum well layer so as to form a energy difference V0 between the bottom of the conduction band of the quantum well layer and the bottom of the conduction band of the barrier layer. The relationship represented by formula (I) is satisfied:Lz