Enhancement of time-delay measurement accuracy of an insufficient stimulated Brillouin scattering based pulse compression system via lock-in detection

We demonstrate a novel scheme to increase the accuracy of time-delay measurement of an insufficient stimulated Brillouin scattering (ISBS) based pulse compression system. It is realized by relating the time delay with the pulse compression gain, which is accumulated by a lock-in amplifier (LIA). We theoretically demonstrate that the time delay is proportional to the accumulated gain via the LIA. In the experiment, the pulse compression gain is accumulated through lock-in detection. It narrows down the detection bandwidth and reduces the influence from the broadband noise. The time-delay measurement is completed in a real-time manner and thus provides a possible solution to realizing a high-speed process in the future. The accuracy of measurement of a linear frequency modulated (LFM) signal with a bandwidth of 1 GHz is 1 ns.