Patent ID: 7880187

Claim:
A semiconductor light emitting device comprising: an active layer for emitting light upon injection of current; a pair of clad layers sandwiching the active layer, the pair of clad layers having a band gap that is wider than a band gap of the active layer; at least one optical absorption layer disposed outside at least one clad layer of the pair of clad layers, the light emitted by the active layer being output to outside of the semiconductor light emitting device through the optical absorption layer, and the optical absorption layer having a band gap that is wider than the band gap of the active layer and narrower than the band gap of the pair of clad layers; and electrodes for injecting the current into the active layer; wherein one of the electrodes is disposed outside the optical absorption layer and is patterned so that light generated in the active layer can be output to an outer space through the optical absorption layer; wherein the band gap of the optical absorption layer is narrower than a band gap corresponding to a wavelength, which is shorter than a wavelength at which a radiation spectrum of the active layer has a maximum value, and at which an intensity of the radiation spectrum of the active layer is 10% of the maximum value of the radiation spectrum of the active layer; wherein the wavelength at which the radiation spectrum of the active layer has the maximum value is an infrared range; and wherein the active layer is made of InGaAs and the optical absorption layer is made of AlGaAs.