Patent ID: 8772801

Claim:
A near-infrared light-emitting element on a III-V group compound semiconductor substrate, comprising: an active layer having a multi-quantum well (MQW) structure, the multi-quantum well structure including layered type 2 pairs; and an upper cladding layer and a lower cladding layer disposed on opposite sides of the active layer, the upper cladding layer being more distant from the substrate than the lower cladding layer, wherein the type 2 pairs include a plurality of pair thickness groups having different thicknesses, including a first pair thickness group and a second pair thickness group, the first pair thickness group includes 10 pairs or more and 100 pairs or less, each monolayer of the pairs having a thickness of 1.5 nm or more and less than 3.5 nm, the second pair thickness group includes 10 pairs or more and 100 pairs or less, each monolayer of the pairs having a thickness of the minimum thickness (a second group minimum thickness) or more and 7 nm or less, the minimum thickness being larger than the maximum monolayer thickness 3.5 nm of the first pair thickness group, and the light-emitting element has an oscillation peak wavelength of 1.7 μm or more and 3.0 μm or less.