A simple computational formalism has been derived for the analysis of splic
ing and return losses between different optical waveguides. It has been fou
nd that the splicing loss can be approximated by the overlap integral metho
d as long as total reflectance is negligible, The reciprocity of splicing l
oss between two single-mode waveguide is theoretically confirmed while retu
rn loss is found nonreciprocal. The return loss can be tolerably approximat
ed by simple Fresnel formula except near the resonance. When close to the r
esonance, the deviation from Fresnel approximation is found to be strongly
dependent on the structure of the waveguide and the refractive index differ
ence between the core and clad.