Abstract

During the last fifteen years many intriguing scientific and industrial applications of terahertz (THz) electromagnetic radiation have been proposed. For this reason the development of new methods for the generation and detection of THz radiation is very actual topic today. Optical rectification utilizing femtosecond pulses with tilted pulse fronts¹ is probably one of the most promising techniques for the generation of high-energy subpicosecond THz pulses. Recently it was shown that this technique allows to rich very high (~10%) optical-to-THz quantum conversion efficiency². Here we report experimental observations of the spectral modifications of ultrashort laser pulses caused by high-efficiency optical rectification. Moreover, we assert that the observed spectral modifications can be used to evaluate the absolute energy of generated THz pulses without calibrated THz detector. Abilities to obtain more than 100% optical-to-THz quantum conversion efficiency by phase-matched optical rectification are discussed.

© 2007 IEEE