Abstract

THz-wave generation with femtosecond laser pulses has attracted much attention recently as a new THz light source in spite of its poor coherency. On the other hand, there had been several reports on the wide-tunable coherent THz-wave generation with the parametric process based on LiNbO₃ Raman laser.^1-3 However, as far as we know, no reports have been published on this matter since 1975. Coherent THz-wave is important, such that reviving this coherent and tunable THz-generation technology is necessary. However, large absorption loss of LiNbO₃ at THz range is a problem for the efficient coupling of the radiation. In this report, a novel grating coupler on the LiNbO₃ surface is introduced to extract 250 times stronger THz output than that obtained from the conventional cut-exit method.

© 1996 Optical Society of America