Abstract

Fiber Bragg gratings (FBGs) are well-known to be essential elements in optical communications, optical fiber based sensors and fiber lasers [1]. One of the most recent methods for fabricating FBGs is referred to as point-by-point inscription and uses femtosecond duration pulses of an infrared laser tightly focused to the fiber core region, such that every pulse forms a single grating period [2]. The periodicity of the grating is controlled by moving the fiber along its axis using translation stages at a pre-defined speed for a known repetition rate of the laser. A multi-photon absorption process is responsible for the local refractive index modification induced by a single pulse. Gratings obtained using point-by-point inscription can for example be used at much higher temperatures than those fabricated using conventional UV laser based inscription.

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