Direction-sensitive detection of a spinning object using dual-frequency vortex light

Rotational Doppler effect (RDE) has attracted much attention in recent years which opens new avenues to angular velocity measurement. However, most previous studies used single-frequency vortex light as the detection beam so that the rotational Doppler signal is in the low frequency domain where most of noise signals exist. In this article, we use the dual-frequency 2-fold multiplexed vortex light as the probe beam and transform the Doppler signals from the low frequency domain to the high frequency domain successfully. The results show hardly any noise compared with the measurement in the low frequency domain. More importantly, the direction of rotation can be obtained directly by comparing the modulated signal and the reference signal. Our work demonstrates a new detection method for the RDE and provides a reference for its practical application. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

In this article, the authors successfully transformed the rotational Doppler signals from the low frequency domain to the high frequency domain using dual-frequency 2-fold multiplexed vortex light as the probe beam. The results showed minimal noise compared to measurements in the low frequency domain. The direction of rotation could be directly obtained by comparing the modulated signal and the reference signal.