Fiber Coupled THz Time-Domain Spectrometer with 10 THz Bandwidth

We present a fiber coupled THz time-domain spectrometer exhibiting a record bandwidth of 10 THz. This significant increase in bandwidth was enabled by improving the photoconductive antennas (PCAs) used as THz emitter and receiver. In particular, we identified absorption in the InP:Fe substrate of the PCAs as the main limiting factor for the spectral bandwidth. To minimize this absorption, we developed a wafer-scale substrate transfer process for the thin photoconductive InGaAs layer from the InP:Fe substrate onto a low-loss, high-resistivity float-zone Si substrate. Hence, our work shows a promising path towards ultrabroadband fiber coupled THz TDS systems.