A photolithographic method is described for fabricating refractive index Bragg gratings in photosensitive optical fiber by using a special phase mask grating made of silica glass. A KrF excimer laser beam (249 nm) at normal incidence is modulated spatially by the phase mask grating. The diffracted light, which forms a periodic, high-contrast intensity pattern with half the phase mask grating pitch, photoimprints a refractive index modulation into the core of photosensitive fiber placed behind, in proximity, and parallel, to the mask; the phase mask grating striations are oriented normal to the fiber axis. This method of fabricating in-fiber Bragg gratings is flexible, simple to use, results in reduced mechanical sensitivity of the grating writing apparatus and is functional even with low spatial and temporal coherence laser sources.

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Persistent URL dx.doi.org/10.1063/1.108786
Journal Applied Physics Letters
Citation
Hill, K.O. (K. O.), Malo, B. (B.), Bilodeau, F. (F.), Johnson, D.C. (D. C.), & Albert, J. (1993). Bragg gratings fabricated in monomode photosensitive optical fiber by UV exposure through a phase mask. Applied Physics Letters, 62(10), 1035–1037. doi:10.1063/1.108786