Abstract: A metallic ring is made of two metals, wherein one metal forms a major arcuate portion and the other a minor arcuate portion of the ring, thereby forming a thermocouple-type structure as a result of the two inter-metallic junctions. The metallic ring supports a surface plasmon whose energy is matched to the energy, i.e. wavelength, of an incident light beam so that the oscillating electromagnetic field of the light resonates with the plasmon. The resonating plasmon causes a temperature difference to arise between the two inter-metallic junctions in the ring. The different Seebeck coefficients of the two metals results in the temperature difference causing a net current to flow around the ring, which in turn generates a magnetic field. Such a thermoelectric metamaterial ring transforms high frequency optical energy into long duration magnetic radiation pulses in the terahertz range.