Gas sensor based on terahertz wave band

The invention discloses a gas sensor based on a terahertz wave band. The gas sensor can be applied to gas detection. The gas sensor based on the terahertz wave band comprises a first distributed Bragg reflector, a metal layer and a second distributed Bragg reflector which are arranged in a single row, wherein the metal layer is positioned between the first distributed Bragg reflector and the second distributed Bragg reflector; the first distributed Bragg reflector and the second distributed Bragg reflector have different center frequencies; the first distributed Bragg reflector is provided with a plurality of first entity regions and first space regions which are alternately distributed along a first direction; the second distributed Bragg reflector is provided with a plurality of second entity regions and second space regions which are alternately distributed along the first direction; the refractive indexes of the first entity region and the second entity region are greater than the refractive index of gas