Spectrum collapse in a 7-core Yb-doped fiber laser with an array of fs-inscribed fiber Bragg gratings

Fiber Bragg grating inscription assisted by a spatial light modulator

In this Letter, we proposed a new technique for point-by-point fiber Bragg grating (FBG) writing in a static fiber by using a spatial light modulator to control the position of the focal point inside the fiber core. Various types of short-length FBGs (uniform, phase-shifted, and apodized) were demonstrated by this inscription technique. Moreover, the capability to tailor the transverse dimension of a grating pitch from a single point to more complex shapes, such as a wide plane covering a whole fiber core or a transverse ring, was shown.