FIELD: optics, optical communication. SUBSTANCE: given single-mode optical fiber includes first core displaying constant refractive index within bounds of specified radius from center of optical fiber, second core that covers first core and has refractive index which decreases from refractive index of first core with growth of its radius and sheath which covers second core and has refractive index lesser than minimal refractive index of second core. EFFECT: given optical fiber shows low dispersion and losses. 5 cl, 11 dwg
