Entrainment of polaritons in rotating ruby

A luminescent trace has been observed in a ruby crystal (Al$_2$O$_3$:Cr$^{3+}$) that rotates at a frequency of 2 to 200 Hz and is irradiated by 532-nm coherent electromagnetic radiation. A method has been proposed to determine the lifetime of the excited electronic state of chromium ions from the measurement of the length of an arc of the trajectory of a light spot on the surface of a rotating ruby single crystal. A “comet trace” formed at the passage of radiation through the rotating crystal near the absorption band of the material has been detected inside the ruby crystal. It has been shown that the theory based on the analysis of the motion of polaritons in the rotating reference frame is in satisfactory agreement with experimental results.