THz semiconductor laser incorporating a controlled plasmon confinement waveguide

A semiconductor laser comprises an active region ( 12 ) which, in response to a pumping energy applied thereto, can produce a stimulated emission of radiation with a central wavelength (lambda) in the far infrared region, and a confinement region ( 16, 18, 22 ) suitable for confining the radiation in the active region ( 12 ), and comprising at least one interface ( 16 a, 16 b, 22 a) between adjacent layers that is capable of supporting surface plasmon modes generated by an interaction of the interface with the radiation. The confinement region ( 16, 18, 22 ) comprises a wave-guide layer ( 16 ) which is delimited on opposite sides by a first interface and by a second interface ( 16 a, 16 b). The guide layer ( 16 ) is doped in a manner such that the first and second interfaces ( 16 a, 16 b) are capable of supporting the plasmon modes, respectively, and is of a thickness (d) such as to bring about the accumulation of the plasmon modes in proximity to the first and second interfaces ( 16 a, 16 b), outside the layer ( 16 ), and substantially a suppression of the plasmon modes, inside the layer.