Improving the accuracy of distance measurements based on beat frequency detection of a dual-frequency optoelectronic oscillator

A high-accuracy distance measurements (DMs) approach based on beat frequency detection of a dual-frequency optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The dual-frequency OEO is formed with a single electro-optical modulator and a common length of energy storage fiber, and the beat frequency of the two oscillation signals can be directly achieved after a photodetector. Since the environmental disturbance has the same influence on the lengths of the two loops corresponding to the two oscillation frequencies, the environmental disturbance errors can be greatly reduced by beat frequency detection. In the experiment, we achieved a sensitivity of 49.9375 kHz/mm and a measurement error of +/- 15 mu m. The frequency stability of the beat-frequency signal was 8.57 times higher than the oscillation signal of the measurement loop. (C) 2021 Optical Society of America