High-Tc superconductor (HTS) is a promising material for terahertz (THz) el
ectronics, The THz beam generation from YBa2Cu3O7-delta (YBCO) thin film an
tennas using femtosecond (fs) laser pulses with a wavelength h of around 1.
55 mum is demonstrated. The mechanism of the THz beam generation is reveale
d to be of the one photon excitation process corresponding to an intraband
transition in the in-gap state. The properties of the THz beam generation e
xcited by the 1.55 mum fs laser are similar to that excited by an 800 nm fs
laser.