Abstract

Bragg gratings in optical fibres have been the subject of a very intense activity of research since the first demonstration of the side-writing technique with a UV laser by Meltz et al. in 1989¹. Since then, many improvements have been realised and other techniques have been developed. We present here a novel interferometer which allows a modification of the fringes period by changing only one parameter, the position of two mutually attached mirrors. This new system, in combination with the technique of writing long gratings by the superposition of subgratings while the fibre has an interferometrically controlled motion², gives complete freedom for the design of gratings.

© 1997 Optical Society of America