Periodic-error-free all-fiber distance measurement method with photonic microwave modulation towards

High-accuracy distance measurements with compact configurations and robust operations are necessary in areas ranging from precision engineering to scientific missions. Here, we report a precise and accurate amplitude-modulation-based all-fiber distance measurement method without periodic errors. To realize an all-fiber configuration towards on-chip devices in the future, certain selective components for easy fabrication on the chip scale were employed. Despite this constraint, sub-100 nm precision was demonstrated with the help of the all-photonic microwave mixing technique introduced in our previous work. In this paper, accuracy as another important factor for measuring distances was investigated to ensure better performance than in previous studies with an optical amplitude-modulation technique. By performing theoretical and experimental analyses of the periodic error while blocking electrical crosstalk signals and optimizing signal processing, accuracy of 2.6 μm (1 σ) was achieved in terms of measurement linearity according to a comparison with a laser displacement interferometer. With the best capabilities of precision and accuracy, the proposed all-fiber distance measurement method is expected to be utilized in diverse long-distance applications, such as large-machine axis tool work and formation flying by multiple satellites. Further, this study demonstrates the possibility of developing an on-chip-based distance-measuring device for the fourth industrial revolution.