Development of Fiber Gratings Inscribed by Femtosecond Laser

Fiber gratings have the characteristics of anti-electromagnetic interference, good causticity resistance, strong plasticity, small size, light in mass, and natural compatibility with optical fiber systems. They have obtained wide applications in the fields of fiber sensing, fiber communications, fiber lasers, and so on. At present, the common fiber grating manufacturing methods include ultraviolet exposure, CO(2 )laser inscribing and femtosecond laser inscribing. The advent of femtosecond lasers has greatly simplified the manufacturing process of fiber gratings. As its inscribing mechanism is different from the common ultraviolet exposure method, it does not need to carry hydrogen treatment on the fiber, which is very useful for fabricating high-performance gratings on ultra-large core fibers. According to whether a phase template is used, the fiber grating fabrication using femtosecond laser is generally divided into two ways: direct inscribing and phase mask method. This paper reviews the development of fiber gratings using femtosecond lasers at home and abroad from the perspective of inscribing methods. By summarizing and analyzing the characteristics of various femtosecond inscribing methods and the application of the fabricated gratings, we point that they potentially have important and broad applications in distributed fiber sensing, wavelength division multiplexing of fiber communication, multi-wavelength lasers, high-power fiber lasers, etc.