FIELD: fiber optics. SUBSTANCE: gear includes radiation source generating ultraviolet laser radiation, mirror intended for reflection of ultraviolet laser radiation generated by light source at specified angle and for change of path of radiation propagation, lens focusing laser radiation which path changes by means of mirror, scattering element dispersing laser radiation passed through lens and amplitude mask placed between scattering element and optical fiber possessing transmission region through which dispersed laser radiation is periodically transmitted to optical fiber. Width of band of fiber-optical diffraction grating with large period can be adjusted with the aid of control over laser beam irradiating optical fiber. Amplitude masks can be manufactured at low cost and their threshold destruction power can be high. In correspondence with another variant gear can have two amplitude masks spaced apart along fiber. EFFECT: enhanced manufacturing precision. 19 cl, 12 dwg, 2 tbl
