FIELD: fiber-optical communication lines. SUBSTANCE: filter and fiber include core in which diffraction grating with large period is formed, jacket containing core, first coat laid above section of jacket not embracing diffraction grating and second coat laid above section of jacket embracing diffraction grating and made of material which refractive index grows with rise of temperature. Refractive index of second coat is less than refractive index of jacket. Second coat is used to shift communication wave of diffraction grating caused by growth of refractive index in direction opposite to shift of communication wave of diffraction grating caused by difference of refractive indices of core and jacket. EFFECT: simple temperature compensation of parameters of filter is ensured. 5 cl, 13 dwg
