Research on the effect of atmospheric turbulence on the rotational Doppler effect

Due to their unique helical wavefront structure and orbital angular momentum (OAM) properties, vortex beams have demonstrated remarkable potential in rotational velocity measurement applications utilizing the rotational Doppler effect (RDE). However, in remote velocity sensing, distortions induced by atmospheric turbulence pose a significant challenge to their practical implementation. This paper experimentally investigates the impact of mode dispersion caused by atmospheric turbulence on the RDE of OAM superposition states, including spot profile distortions, waveform deformation, and broadening of the rotational Doppler shift (RDS) peaks in the frequency spectrum. The experimental results show that the velocity measurement error caused by turbulence distortion expands from 0.34% to 1.06%. The increase in turbulence intensity leads to an increase in the OAM modes dispersion degree, a significant reduction in the RDS amplitude, and an increase in the sideband amplitude. This work not only elucidates the turbulence-induced degradation mechanisms in RDE-based sensing but also provides an experimental foundation for the development of improving the robustness of remote velocimetry systems under realistic atmospheric conditions.