Detection sensitivity of electrooptic sampling for continuous-wave terahertz sources throughout broad frequency range

Broadband THz detection technique is required for high precision molecular gas spectroscopy, wireless communications, and so on. In this work, Sensitivities of electrooptic (EO) sampling method for the frequency measurement of continuous-wave terahertz (THz) sources were compared from 0.1 to 3.1 THz. By using a femtosecond fiber laser to gate the EO sampling, we observed beat signals between the harmonics of laser repetition frequency and the THz sources. The signal to noise ratio linearly decreases as the power of the THz sources decreases, indicating that the sensitivity is almost constant throughout this frequency range.