An infrared detector comprising: a substrate; a first electrode, disposed on the substrate; an infrared-absorbing layer disposed on the first electrode, wherein the infrared-absorbing layer absorbs incident infrared light in a specific wavelength band and generates a current corresponding to absorbed infrared light; and a second electrode disposed on the infrared-absorbing layer; wherein the infrared-absorbing layer comprises: a first semiconductor layer comprising a first component; a plurality of quantum dots comprising a second component, different from the first component, wherein the plurality of quantum dots are spaced apart from each other and disposed on the first semiconductor layer; and a second semiconductor layer comprising the first component and the second component and covering the plurality of quantum dots; characterized in that a range of the ratio of the second component to the first component is from 0.379:0.621 to 0.530:0.470 and a range of a center wavelength of the specific wavelength band is 1350 nm to 1650 nm; wherein the specific wavelength band is determined by a content of the second component in the infrared-absorbing layer; wherein a center wavelength of the specific wavelength band is proportional to a content of the second component in the infrared-absorbing layer; and wherein the first component is GaAs and the second component is InAs. a substrate; a first electrode, disposed on the substrate; an infrared-absorbing layer disposed on the first electrode, wherein the infrared-absorbing layer absorbs incident infrared light in a specific wavelength band and generates a current corresponding to absorbed infrared light; and a second electrode disposed on the infrared-absorbing layer; wherein the infrared-absorbing layer comprises: a first semiconductor layer comprising a first component; a plurality of quantum dots comprising a second component, different from the first component, wherein the plurality of quantum dots are spaced apart from each other and disposed on the first semiconductor layer; and a second semiconductor layer comprising the first component and the second component and covering the plurality of quantum dots; characterized in that a range of the ratio of the second component to the first component is from 0.379:0.621 to 0.530:0.470 and a range of a center wavelength of the specific wavelength band is 1350 nm to 1650 nm; wherein the specific wavelength band is determined by a content of the second component in the infrared-absorbing layer; wherein a center wavelength of the specific wavelength band is proportional to a content of the second component in the infrared-absorbing layer; and wherein the first component is GaAs and the second component is InAs. a first semiconductor layer comprising a first component; a plurality of quantum dots comprising a second component, different from the first component, wherein the plurality of quantum dots are spaced apart from each other and disposed on the first semiconductor layer; and a second semiconductor layer comprising the first component and the second component and covering the plurality of quantum dots; characterized in that a range of the ratio of the second component to the first component is from 0.379:0.621 to 0.530:0.470 and a range of a center wavelength of the specific wavelength band is 1350 nm to 1650 nm; wherein the specific wavelength band is determined by a content of the second component in the infrared-absorbing layer; wherein a center wavelength of the specific wavelength band is proportional to a content of the second component in the infrared-absorbing layer; and wherein the first component is GaAs and the second component is InAs.