Highly efficient terahertz radiation from YBa2Cu3O7-delta thin film log-periodic antennas

We report on the radiation power of the terahertz (THz) beam from YBa2Cu3O7 -delta (YBCO) thin film antennas. InSb hot-electron bolometer is used to es timate the radiation power after being calibrated in the THz beam generatio n and detection system. The 100-nm-thick and 30-mum-wide YBCO thin film bri dges are connected to a self-complimentary log-periodic toothed planar ante nna or a bow-tie antenna. Femtosecond optical pulses are focused onto the c enter bridge of the antennas being biased with a current up to 1 A. The det ected power increases in proportion with increasing bias current, and reach es over 22 muW in the average at an excitation power of 98 mW. (C) 2001 Els evier Science BY. All rights reserved.