Abstract

The rectification of femtosecond optical pulses in electrooptic crystals by the electrooptic Cherenkov effect has proved to be an effective technique for generating femtosecond electrical pulses having base bandwidths of many terahertz.¹ A major disadvantage, however, of this approach has been the difficulty of extracting these electrical pulses from the crystals due to total internal reflection. In lithium tantalate, the crystal used for these experiments, the index of refraction in the submillimeter wave band is 6.53. This results in an escape cone of only 8°. In the normal geometry used, the signal is thus totally internally reflected, which severely limits the applications of this technique for measuring the properties of materials.

© 1989 Optical Society of America