Patent ID: 7933305

Claim:
A device for generating or detecting a terahertz wave, said device comprising: a substrate; a gain medium provided on the substrate, said gain medium having a quantum well structure formed of a semiconductor material, and said gain medium giving a gain to the terahertz wave by transition between subbands created in at least a quantum well in the quantum well structure; a plurality of reflectors for confining the terahertz wave in a predetermined frequency range substantially perpendicularly to a face of the substrate; and a spacer layer for spacing the reflectors from each other at a predetermined distance with the gain medium being sandwiched between the reflectors, said spacer layer being formed of a material different from a crystalline material of the gain medium, wherein the predetermined distance between the reflectors is determined by a thickness of the spacer layer such that the predetermined distance approximately equals to an equivalent wavelength of the terahertz wave in the device, wherein the spacer layer is composed of Si, organic resin, or ceramics, wherein the terahertz wave is reflected in a reflection area on at least one reflector among the plurality of reflectors, and wherein the reflection area on the at least one reflector is in contact with the spacer layer.