摘要 |
A grating formation method comprises the steps of accelerating ions; causing the accelerated ions to pass through a mask having a shape corresponding to the grating; and implanting the ions, which have passed through the mask, into the core, to form refractive index-variation portions for the grating in the core. The other formation method comprises the steps of accelerating ions, converging an ion beam formed of the accelerated ions, to make a beam diameter identical with or smaller than a width of refractive index-variation portions in a direction of the central axis of the optical waveguide so as to provide a converged ion beam; and intermittently irradiating the converged ion beam to the core, while moving an irradiation position in the direction of the central axis, to implant the ions into the core so as to form the refractive index-variation portions in the core.
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