It was estimated that N ≈ 10 6 ∼ 10 12 per effective cavity mode , and Ω R,N ≈ 100 cm -1 for the typical VSC experiments . The strong coupling condition in the experiments is achieved when Ω R,N ≫ τ -1 c and the optical spectra of the molecule-cavity hybrid system have a peak splitting. However, the fundamental mechanism of the experimentally observed VSC effect (which happens under the collective coupling regime, Eq. 36) remains to be explained.