where g is coupling strength by some source and w_{m} is harmonic frequency of oscillator.The quantum effects are being controlled by this relation. More the coupling strength batter will be the quantum effects such as Squeezing, entanglement and cooling etc. In general its a ratio of two frequencies. But, what is the physical interpretation behind this and how one frequency controls the other?.
Have a look at this Hamiltonian:
https://en.wikipedia.org/wiki/Cavity_optomechanics#Mathematical_treatment
A term with g has a position operator x_m, while a term with w_m doesn't. In all other respects these terms are identical. The ratio g/w_m then corresponds to the normalised coupling strength.
@ Alexxander
Dear Sir, Thanks, but I know its a normalized coupling strength. Could you please tell me the physical interpretation of this ratio.?
Well, I'd say that it describes how quickly the coupling occurs relative to the oscillation in the cavity. At least that's my understanding based on that Hamiltonian. Cheers!
g_{0} has units of frequency/distance and is essentially a measure of how much a single photon will move the mirror a given distance per unit of time. Multiplied by the photon number and the distance, it says how much energy is involved in the electromagnetic field "pushing" the mirror. Hope that's useful.