A 1550-nm-wavelength compatible photoconductive microprobe transceiver for Terahertz near-field reflection measurements

THz-radiation based measurements in reflection-mode provide several advantages over transmission-mode configurations such as depth information and single side sample access useful e.g. for the inspection of multi-layer structures, detection of buried defects or the investigation of samples on THz opaque substrates. We present here an InGaAs:Rh-based photoconductive near-field transceiver probe operating at 1550 nm excitation wavelength which can be directly driven by modern fiber-based THz TDS systems without requiring optical frequency-doubling units. The new probe will foster the configuration of fiber-based robotic scanning systems thanks to the simplification of the optical front-end module.