Contact printing of Bragg gratings in optical fibers: rigorous diffraction analysis

The fabrication of Bragg gratings inside the core of single-mode optical fibers has been greatly simplified by the application of contact printing [Appl. Phys. Lett. 62, 1035 (1993)]. According to this technique, the fiber is placed in proximity to an appropriate phase grating, which is illuminated with nominally monochromatic UV light. The transmitted light is redistributed into an ideally sinusoidal variation of optical intensity (more properly, irradiance), which is imprinted into the core as a result of photoinduced refractive index changes. In accordance with normal practice in this field, intensity is used instead of optical intensity throughout the text. The main advantage of such a writing method, apart from its simplicity, is that the illumination source need not be highly coherent. Rigorous analysis of this method is given with a new phase grating design.