Patent ID: 11740396

Abstract:
An optical device comprises an optical filter having a substrate and a multilayer film, and an infrared light emitting and receiving device having a first conductive-type semiconductor layer, an active layer, and a second conductive-type semiconductor layer. The multilayer film has layers with different refractive indexes formed on at least one side of the substrate, in which first and second layers having refractive indexes of 1.2 or more and 2.5 or less, and 3.2 or more and 4.3 or less, respectively, in a wavelength range of 6 μm to 10 μm are alternately stacked. The optical filter includes a wavelength range having an average transmittance of 70% or more with a width of 50 nm or more in a wavelength range of 6 μm to 10 μm, and has a maximum transmittance of 10% or more in a wavelength range of 12.5 μm to 20 μm.