  Dual terahertz (THz) comb spectroscopy is a promising methods for high
accuracy, high resolution, and broadband THz spectroscopy because the
mode-resolved THz comb spectrum possesses both characteristics of broadband THz
radiation and narrow-linewidth continuous-wave THz radiation and all frequency
mode of THz comb can be phase-locked to a microwave frequency standard.
However, requirement of stabilized dual femtosecond lasers has often hindered
wide use of this method. In this article, we demonstrated the adaptive
sampling, dual THz comb spectroscopy, enabling use of free-running dual
femtosecond lasers. To correct the non-linearity of time and frequency scale
caused by the laser timing jitter, an adaptive sampling clock is generated by
dual THz-comb-referenced spectrum analysers and is used for a timing signal in
a data acquisition board. The demonstrated results did not only indicate the
implementation of dual THz comb spectroscopy with free-running dual lasers but
also implied the superiority of its spectroscopic performance over the dual THz
comb spectroscopy with stabilized dual lasers.
