Detector for terahertz electromagnetic waves, said detector comprising: - at least one first device configured to collect and transform an incident electromagnetic wave, having a terahertz frequency within a terahertz frequency band, into a measurable mechanical response; and - a detection device for detecting an output signal representative of the measurable mechanical response; said first device comprising a first element and an opposite element forming with the first element a capacitive gap; said first element being a mechanical resonator having a mechanical resonance frequency and being configured to response mechanically to the action of a force stemming from an electric field; wherein said electric field is generated between at least one first electric pole induced in said first element, by first electric charges having a first electrical sign, and at least one second electric pole induced in said opposite element, by second electric charges having a second electrical sign opposite to the first electrical sign; wherein the first device is a terahertz optomechanical transducer which is a terahertz electromagnetic resonator made at least of metal, configured by its geometric characteristics and dimensions to collect the incident terahertz electromagnetic wave and to transform the incident electromagnetic wave into a measurable mechanical response; the terahertz frequency of the incident electromagnetic wave corresponding to the electromagnetic resonance frequency of the terahertz electromagnetic resonator or being in a response frequency bandwidth of the terahertz electromagnetic resonator; wherein the terahertz electromagnetic resonator comprises the first element and the opposite element; wherein the first element and the opposite element comprise each a support layer and an electrically conductive layer which is a metal pattern; wherein the electric field is generated by interaction of said incident electromagnetic wave with electric charges in said terahertz electromagnetic resonator; wherein the first electric charges and the second electric charges alternate in signs between the first and the second electric poles (5, 6) in time at the terahertz frequency of the incident electromagnetic wave. - at least one first device configured to collect and transform an incident electromagnetic wave, having a terahertz frequency within a terahertz frequency band, into a measurable mechanical response; and - a detection device for detecting an output signal representative of the measurable mechanical response; said first device comprising a first element and an opposite element forming with the first element a capacitive gap; said first element being a mechanical resonator having a mechanical resonance frequency and being configured to response mechanically to the action of a force stemming from an electric field; wherein said electric field is generated between at least one first electric pole induced in said first element, by first electric charges having a first electrical sign, and at least one second electric pole induced in said opposite element, by second electric charges having a second electrical sign opposite to the first electrical sign; wherein the first device is a terahertz optomechanical transducer which is a terahertz electromagnetic resonator made at least of metal, configured by its geometric characteristics and dimensions to collect the incident terahertz electromagnetic wave and to transform the incident electromagnetic wave into a measurable mechanical response; the terahertz frequency of the incident electromagnetic wave corresponding to the electromagnetic resonance frequency of the terahertz electromagnetic resonator or being in a response frequency bandwidth of the terahertz electromagnetic resonator; wherein the terahertz electromagnetic resonator comprises the first element and the opposite element; wherein the first element and the opposite element comprise each a support layer and an electrically conductive layer which is a metal pattern; wherein the electric field is generated by interaction of said incident electromagnetic wave with electric charges in said terahertz electromagnetic resonator; wherein the first electric charges and the second electric charges alternate in signs between the first and the second electric poles (5, 6) in time at the terahertz frequency of the incident electromagnetic wave.