Theoretical and empirical comparison of coupling coefficient and refractive index estimation for coupled waveguide fiber

Power transmission and coupling of coupled waveguidefibers are affected on the coupling coefficient. The coupling coefficients obtained in experimental results vary in widely. The coupling coefficients have a function of separation of fiber axis and refractive index of core and cladding. For the empirical formula,coupling coefficient is calculated from experimentalresult of coupling ratio distribution from 1% until 75%. Theoretically, the coupling coefficient has a dependence of some parameters resulting in a sinusoidal curve. Both empirical and theoretical formulae are compared to obtain new phenomena of the refractive index of fibers after fusion.