Construction method for large size Bragg grating within optical fiber

摘要

The exposure of the moving optical fiber ensures that a grating pattern of any chosen length can be produced. The procedure comprises the exposure of the fiber (1) to mobile interference fringes (14) from an ultraviolet light. This induces variations of refractive index in the material of the fiber core. The fiber is moved along at the same time as being exposed to the UV. The fringes are obtained by introducing into one arm of an interferometer a frequency shifter (4) - for example an acousto-optic device. It is possible to generate a variation in the spatial frequency of the grating by variation of the shift frequency.