This paper investigates the assumption of spiralshaped index leads to an optimal result for the optical fiber modes. It also shows how to decrease the effect of optical fibers parameters such as attenuation and dispersion on the quality of transmitted signals, and to improve it into an acceptable form. The dielectric permeability tensor εij related to the curvature and torsion parameters ( χ , υ ) in the coordinates system ( r, φ ) was analyzed. The dependence of εij tensor on the bent on spiral optical fiber parameters was mathematically calculated. Also to study the exchange of power between the waves HEo 11 and HEe 11 .The Transient attenuation dependence on spiral parameters of optical fiber with a length of (one kilometer) as a case study will be studied also.