Patent ID: 7382806

Claim:
A semiconductor laser comprising: an active region ( 12 ) which, in response to a pumping energy applied thereto, produces a stimulated emission of radiation with a central wavelength (λ) in the far infrared region, and at least one confinement region ( 16 , 18 , 22 ) for confining the radiation in the active region ( 12 ) and comprising at least one interface ( 16 a , 16 b , 22 a ) between adjacent layers for supporting surface plasmon modes generated by an interaction of the interface with the radiation, wherein the at least one 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 ) being doped in a manner such that the first and second interfaces ( 16 a , 16 b ) support the plasmon modes, respectively, and the guide layer ( 16 ) being 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, wherein the mode intensity of the plasmon modes in proximity to the second interface ( 16 b ) is similar to the mode intensity of the plasmon modes in proximity to the first interface ( 16 a ).