Plane-by-Plane Inscription of Grating Structures in Optical Fibers

Plane-by-plane fabrication of fiber Bragg gratings in optical fibers using a short-pulse femtosecond IR laser is proposed and demonstrated. By incorporating a cylindrical lens in the fabrication setup, a plane of index modification can be directly inscribed in the fiber core by a single laser pulse. The planes of index modification are produced in the core of a free-standing fiber without an oil immersion objective. This plane-by-plane method simplifies the direct grating inscription process and allows for the fabrication of complicated grating structures.