A long-period grating (LPG) written in the cladding of an optical fiber is demonstrated. The optical fiber is specially designed and manufactured, which cladding is photosensitive, and core is not The cladding LPG is written in by illuminating a cladding photosensitive fiber with an UV lamp through an amplitude grating mask. The cladding LPG is compared with a core LPG manufactured in the same way, and the property of the cladding LPG is different from that of the core LPG. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2425-2427, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26269