Electromagnetic wave detector with an optical coupling surface comprising lamellar patterns

A detector comprising:

• a multiple quantum well structure operating on interband or intersubband transitions by absorption of radiation having a wavelength λ each quantum well structure comprising:
• optical coupling means for coupling said radiation, wherein the coupling means comprise a set of first elongate, narrow diffractive lamellar features that are distributed along at least a first direction and a set of second elongate, narrow diffractive lamellar features that are distributed along at least a second direction, said first and second directions being mutually perpendicular and lying in a plane parallel to the plane of the multiple quantum well structure;
• wherein the first lamellar features and the second lamellar features are distributed so as to form concentric rectangles or squares, the electromagnetic wave detector comprising a multilayer stack produced on a surface of a substrate, said stack comprising the multiple quantum well structure and external layers, the lamellar features being etched within one external layer.