US Patent 7880187 Semiconductor light emitting device having narrow radiation spectrum

Radiation occurs when current is injected into an active layer from electrodes. A pair of clad layers is disposed sandwiching the active layer, the clad layer having a band gap wider than a band gap of the active layer. An optical absorption layer is disposed outside at least one clad layer of the pair of clad layers. The optical absorption layer has a band gap wider than the band gap of the active layer and narrower than the band gap of the clad layer. A spread of a spectrum of radiated light can be narrowed.