SOA-based optical processing for terahertz time-domain spectroscopy

All-fibre control of a terahertz time-domain spectroscopy system based on photoconductive antennas fed with optical sources in the telecom band is demonstrated. A semiconductor optical amplifier (SOA) is used to obtain continuously tunable delays on 100 fs optical pulses. Additionally, the modulation required to carry out lock-in detection can be simultaneously performed avoiding mechanical choppers or high-voltage alternate biasing of the transmitter antenna.