A quantum photodetection element (P 1, P 2,...) for an incident radiation in a spectral band centered around a central wavelength λ 0, exhibiting a front face intended to receive said radiation, and comprising: - a stack of layers made of semi-conducting material forming a PN or PIN junction and comprising at least one layer made of an absorbent semi-conducting material with a cutoff wavelength λ c >λ 0, the stack of layers made of semi-conducting material forming a resonant optical cavity of waveguide type with a given thickness (e); - a metallic reflective layer arranged on a side of the optical cavity, opposite to the side supporting the front face, forming an optical mirror; and - a structure for coupling the incident radiation with the optical cavity, formed of a diffraction grating on the front face and/or a diffraction grating on the rear face, that is to say on a side of the optical cavity, opposite to the side supporting the front face, characterized in that said grating consists of an alternation of two dielectric materials and has a given thickness (h c), period (p) and fill factor (w/p), configured to form one of the following: ∘ a guided-mode resonance at the central wavelength λ 0, allowing an absorption greater than 80% in the absorbent semi-conducting material layer at said central wavelength; ∘ an antiresonance at the radiative wavelength λ rad in the absorbent semi-conducting material layer so as to produce a minimum of absorption in the absorbing semi-conduction material layer at the radiative wavelength λ rad, where the radiative wavelength λ rad is the wavelength for which, at operating temperature, the rate of radiative recombination is a maximum. - a stack of layers made of semi-conducting material forming a PN or PIN junction and comprising at least one layer made of an absorbent semi-conducting material with a cutoff wavelength λ c >λ 0, the stack of layers made of semi-conducting material forming a resonant optical cavity of waveguide type with a given thickness (e); - a metallic reflective layer arranged on a side of the optical cavity, opposite to the side supporting the front face, forming an optical mirror; and - a structure for coupling the incident radiation with the optical cavity, formed of a diffraction grating on the front face and/or a diffraction grating on the rear face, that is to say on a side of the optical cavity, opposite to the side supporting the front face, characterized in that said grating consists of an alternation of two dielectric materials and has a given thickness (h c), period (p) and fill factor (w/p), configured to form one of the following: ∘ a guided-mode resonance at the central wavelength λ 0, allowing an absorption greater than 80% in the absorbent semi-conducting material layer at said central wavelength; ∘ an antiresonance at the radiative wavelength λ rad in the absorbent semi-conducting material layer so as to produce a minimum of absorption in the absorbing semi-conduction material layer at the radiative wavelength λ rad, where the radiative wavelength λ rad is the wavelength for which, at operating temperature, the rate of radiative recombination is a maximum. ∘ a guided-mode resonance at the central wavelength λ 0, allowing an absorption greater than 80% in the absorbent semi-conducting material layer at said central wavelength; ∘ an antiresonance at the radiative wavelength λ rad in the absorbent semi-conducting material layer so as to produce a minimum of absorption in the absorbing semi-conduction material layer at the radiative wavelength λ rad, where the radiative wavelength λ rad is the wavelength for which, at operating temperature, the rate of radiative recombination is a maximum.