REFLECTION PREVENTING FILM FOR OPTICAL FIBER

摘要

PURPOSE:To prevent a breakdown due to energy light absorption by providing a relection preventing film which has such a film thickness distribution that partial that partial light resistance in a film surface is uniform in conformity with the intensity distribution of light on a light input/output end surface of an optical fiber. CONSTITUTION:The annular reflection preventing film 11 having an internal diameter phiB is formed on the light input/output end surface of the optical fiber 10, and a point 9 where the energy density of incident light peaks overlap a film absence part with the diameter phiB. Consequently, deterioration due to the peaking of the incident light intensity is avoided without spoiling the effect of the reflection preventing film, and consequently the incidence of light with larger energy is realized to obtain an optical fiber which has high transmission efficiency and large permissible transmission power.