Method of forming refractive index distribution in light transmission path, and optical filter and method of using the same

摘要

A method of forming a refractive index distribution in a light transmission path including a core and a cladding layer involves steps of applying a photosensitive material layer to the surface of the cladding layer, forming a mask pattern of the photosensitive material layer through photolithography, and irradiating the light transmission path with an electromagnetic wave having a wavelength not exceeding that of visible light and especially a wavelength of X-rays; through the mask pattern, thereby forming in the core a refractive index fluctuation distribution corresponding to the mask pattern.