Measurement of free-space THz pulses via long-lifetime photoconductors

We present the ultrafast measurement and analysis of sub-picosecond freespace THz pulses using long lifetime (=1 ns) photoconducting antennas. We then directly correlate these results with those obtained using typical ultrashort lifetime photoconducting antennas. At low optical gating intensities GaAs based antennas exhibit a higher responsivity and signal-to-noise ratio than typical antennas based on radiation-damaged silicon-on-sapphire. Our power scaling results indicate the potential use of these devices with amplified optical pulses, large-aperture detectors, and THz antenna array