Linear Optical Sampling Detection Electronics with Low Group-delay Distortion

The nonlinear phase of the detection system, employed in high-precision time-frequency transfer using linear-optical sampling with dual optical frequency combs, influences the accuracy of measurement results when relative movement occurs between the comparison parties. We fabricated an electronics detection system with a flat group delay response, and measured its phase characteristics with swept frequency method. The fluctuation of the group delay within the effective detection bandwidth of the detection electronics is controlled to within 250 ps, which correspond to the velocity-dependent measurement error of less than 3.75 fs.