First absolute power measurement of a terahertz time domain spectroscopy system based on InGaAs/InAlAs photoconductors

We present the first absolute power measurement of a photoconductive terahertz (THz) emitter developed for time domain spectroscopy. The broadband THz radiation is generated by a high mobility InGaAs/InAlAs multilayer heterostructure photoconductive emitter packaged into a fiber-coupled housing. For detection a recently developed ultrathin pyroelectric thin-film detector with special conductive electrodes is employed. The detector signal is traceable to the International System of Units since the power responsivity of the detector was calibrated with a standard detector at the German national metrology Institute (PTB). Absolute THz power exceeding 0.1 mW was detected.