Tunable compact asynchronous optical sampling system using Er-doped fiber laser

We report a compact, tunable, self-starting, all-fiber laser-based asynchronous optical sampling（ASOPS） system. Two Er-doped fiber oscillators were used as the pulsed-laser source, whose repetition rate could be set at 100 MHz with a tuning range of 1.25 MHz through a fiber delay line. By employing phase-locked and temperature control loops, the repetition rate offset of the two lasers was stabilized with 7.13 × 10 -11 fractional instability at an average time of 1 s.Its capabilities in the terahertz regime were demonstrated by terahertz time-domain spectroscopy, achieving a spectral bandwidth of 3 THz with a dynamic range of 30 d B. The large range of repetition rate adjustment in our ASOPS system has the potential to be a powerful tool in the terahertz regime.