An optical detector that is sensitive in at least two infrared wavelength ranges: first spectral band and second spectral band; and having a set of pixels, comprising: an absorbent structure disposed on a lower face of a substrate and comprising a stack of at least one absorbent layer made of semi-conductor material; the detector further comprising a plurality of dielectric resonators on the upper surface of said substrate forming an upper surface metasurface, the metasurface configured to diffuse, deflect and focus in the pixels of the detector in a resonant manner, when illuminated by the incident light, a first beam having at least one first wavelength included in the first spectral band and a second beam having at least one second wavelength included in the second band, the metasurface also being configured so that said first and second beams are focused on different pixels of the detector.