Patent ID: 7386016

Claim:
An electrically-pumped THz frequency radiation source comprising: an optical gain material formed substantially of at least one group IV element and doped with at least one dopant having an intra-center transition frequency in a range of about 0.3 THz to 30 THz, the at least one dopant including; a first co-dopant of a first carrier type having a first intra-center transition frequency; and a second co-dopant of the first carrier type having a second intra-center transition frequency; a first electrode electrically coupled to the optical gain material; and a second electrode electrically coupled to the optical gain material: wherein: a first dopant concentration of the first co-dopant is approximately equal to a second co-dopant concentration of the second dopant; and the first intra-center transition frequency is not equal to the second intra-center transition frequency.