Terahertz radiation from optical rectification of a modulated laser pulse

A terahertz source has been developed based on a hybrid of optical rectification and difference frequency generation. The optical pulse from a titanium:sapphire laser system is stretched and modulated using a spatial filtering technique to produce a several picosecond long pulse modulated at the terahertz frequency. A type II phase matched interaction is realized via angle tuning in a gallium selenide crystal. A liquid helium cooled silicon bolometer was used to establish a lower bound of 2 kW on the peak power observed at 1.1 THz. Tunability was demonstrated between 0.7 and 2.0 THz.