Interferometric element, device for detecting a compound comprising an interferometric element and method for detecting a compound

An interferometric element (EI) intended for a device for detecting at least one compound (C) having a resonant absorption over a predetermined spectral region centred on a resonance wavelength λr, said interferometric element comprising at least one detection subset (SE) that is optimised for said resonance wavelength λr and comprising:

• at least two optical cavities of Fabry-Pérot (FP) type having a resonance at said resonance wavelength λr, each cavity comprising a reflecting layer (CR) at said resonance wavelength λr and a partially transparent layer (CT) at said resonance wavelength λr,
• an encapsulation layer (CE) that is impermeable to the compound or compounds to be detected (C) and encapsulating at least one optical cavity, called reference cavity (REF), such that said reference cavity has none of said compound to be detected between the reflecting layer (CR) and the partially transparent layer, the encapsulation layer not encapsulating the second optical cavity, called sensitive cavity (SNS), and the partially transparent layer of the sensitive cavities being permeable to the compound or compounds to be detected (C) such that the sensitive cavity can include the compound or compounds to be detected (C) between the reflecting layer (CR) and the partially transparent layer.