Real-time and high-precision optical time-delay estimation via weak measurement with double-edge filter

Optical time delays play a pivotal role in modern physics and practical applications. We propose and experimentally validate a weak measurement system with a double-edge filter, which enables the real-time, high-precision estimation of varying time delays, and the effective suppression of technical noise. In the experiment, the postselected probe light is processed by the double-edge filter, which is formed by a pair of fiber Bragg gratings positioned symmetrically about the center frequency of the probe light, and subsequently detected by photodetectors. The experimental results demonstrate a time-delay precision of 1.66 attoseconds (as) and real-time estimation capability. With a postselection angle of ${10}^{\ensuremath{-}3}\phantom{\rule{0.16em}{0ex}}\mathrm{rad}$ and the system operating within the most sensitive linear dynamic range, the precision can be further improved to ${10}^{\ensuremath{-}4}$ as. The approach benefits from its high sensitivity and rapid detection, which shows great potential applications in real-time and high-precision time-delay measurements.