THz near-field enhancement by means of dipolar antennas

Generation of high intensity Terahertz radiation in the low frequency region ( f < 5 THz) is still a challenging task. One viable option is the use of resonant metallic structures which act as amplifiers for the impinging radiation. Here we design and realize a set of isolated resonant elements which allow us to reach a 28-fold enhancement of freely propagating THz radiation at f = 1 THz. Interestingly, we experimentally show strong modifications of the antennas resonance which is interpreted in terms of interference effects. These are particularly important in samples thinner than half the spatial pulse length.