where 𝑚 is the resonance order and 𝐿 is the circumference of the MRR. Since 0 depends on 𝑛 𝑒𝑓𝑓 , any change in the refractive index of 1 would produce a spectral shift in the optical resonance due to a change in 𝑛 𝑒𝑓𝑓 . We investigate the spectral shifts using the experimental setup shown in Figure .