Fabrication of long-period fiber gratings by use of focused ion-beam irradiation

Long-period gratings have been made in nonphotosensitive optical fibers by irradiation of the core of a fiber with a focused beam of high-energy proto ns. The irradiated fibers exhibit relatively low loss, even before thermal annealing, and possess strongly wavelength-dependent transmission. The abse nce of a mask provides the opportunity to tailor the grating to a desired p rofile, and a variety of grating profiles were explored. The profile most r esembling a sinusoid was found to produce the cleanest transmission spectra . (C) 2001 Optical Society of America.