Spectral conversion element for electromagnetic radiation

Spectral conversion element (10) for electromagnetic radiation, comprising:

• a two-dimensional support (1), with juxtaposed zones (ZP) which are respectively dedicated to pixels;
• a set of first antennas (2), called Terahertz antennas, which are rigidly supported by the two-dimensional support (1) and sized to have a first absorption peak (P1) for the electromagnetic radiation when a wavelength of the radiation is between 30 μm and 3 mm, corresponding to radiation referred to as Terahertz, at least one of the Terahertz antennas being situated inside each pixel zone (ZP);
• and
• a set of second antennas (3), called infrared antennas, which are also rigidly supported by the two-dimensional support (1) but sized to have a second absorption peak (P2) for the electromagnetic radiation when the wavelength of the radiation is between 1 μm and 30 μm, corresponding to radiation referred to as infrared, at least one of the infrared antennas being situated inside each pixel zone (ZP);
• the conversion element being arranged so that one of the Terahertz antennas (2) and one of the infrared antennas (3) which are both situated in one same pixel zone (ZP), whatever said pixel zone, are thermally coupled with each other, with a thermal resistance which is lower than each other thermal resistance which exists between any one of the Terahertz antennas and any one of the infrared antennas when said Terahertz and infrared antennas are situated in the respective pixel zones which are different.