Terahertz device

A terahertz device, comprising:

• a support substrate including a substrate main surface,
• a terahertz element mounted on the substrate main surface and including an element main surface and an element back surface that face in opposite directions, the terahertz element receiving and detecting an electromagnetic wave in a terahertz band, the terahertz element having a thickness-wise direction that is orthogonal to the element main surface,
• a waveguide mounted on the substrate main surface;
• and
• a reflector disposed on the waveguide so that the reflector and the support substrate are disposed at opposite sides of the waveguide, the reflector including an opening that is open in a direction intersecting the thickness-wise direction and a reflection surface spaced apart and opposed to the element main surface in the thickness-wise direction,
• wherein when an electromagnetic wave is propagated from outside the terahertz device through the opening, the reflection surface reflects the electromagnetic wave toward the terahertz element,
• the reflection surface includes a basal end and a distal end, the distal end being located farther from the terahertz element than the basal end in the thickness-wise direction,
• the waveguide includes a wall surface defining a through hole of the waveguide and a plurality of pipe side surfaces defining an outer surface of the waveguide,
• the wall surface of the waveguide includes a tapered surface that widens from the support substrate as the reflector becomes closer, and
• the distal end of the reflection surface extends to a position that intersects an imaginary line that extends along the tapered surface from a portion of the tapered surface corresponding to one of the plurality of pipe side surfaces.