Abstract: A photodetector according to an embodiment includes: a first semiconductor layer; a porous semiconductor layer disposed on the first semiconductor layer; and at least one photo-sensing element including a second semiconductor layer of a first conductivity type disposed in a region of the porous semiconductor layer and a third semiconductor layer of a second conductivity type disposed on the second semiconductor layer.

Abstract: A photodetector according to an embodiment includes: a semiconductor substrate including a first region and a second region adjacent to the first region; at least one light detection cell including a first semiconductor layer disposed in the first region, a second semiconductor layer disposed between the first semiconductor layer and the semiconductor substrate and including a junction portion with the first semiconductor layer, a third semiconductor layer disposed in the semiconductor substrate separately from the second semiconductor layer, a first electrode on the semiconductor substrate and applying a voltage to the first semiconductor layer, and a second electrode on the semiconductor substrate and applying a voltage to the third semiconductor layer; and a light guide disposed in the second region and guiding incident light to be propagated in a first direction to the junction portion between the first semiconductor layer and the second semiconductor layer.

Abstract: An imaging device includes a light source which irradiates an infrared light including one or more wavelength to a subject; a lens which forms an image of the infrared light transmitting the subject or being reflected from the subject; an infrared detection device including a plurality of pixels which are sensitive to the wavelength; and a filter array which is provided in proximity to the infrared detection device between the lens and the infrared detection device and including a plurality of wavelength filters having different transmission wavelengths.