We report what is believed to be the first example of structural long-period gratings written in pure silica photonic crystal fibers (PCFs). The gratings are realized by periodic collapse of the holes of the PCF by heat treatment with a CO<sub>2</sub> laser. The resulting periodic hole-size perturbation produces core-to-cladding-mode conversion. These results can lead to a new family of structural all-fiber devices that use the unique properties of PCFs.
© 2002 Optical Society of America
G. Kakarantzas, T. A. Birks, and P. St. J. Russell, "Structural long-period gratings in photonic crystal fibers," Opt. Lett. 27, 1013-1015 (2002)