Review of femtosecond laser direct writing fiber-optic structures based on refractive index modification and their applications

Femtosecond (fs) laser pulses direct writing technology has been extensively employed to achieve micro-fabrication in various optical fibers for a broad range of applications. In this paper, the latest development of fiber-optic structures based on refractive index (RI) modification under fs-laser irradiation and their applications are reviewed. Firstly, the processing mechanism of fs-laser direct writing for optical fiber RI modification is described. And then, the fiber-optic structures including various fiber gratings and interferometers based on RI modification are summarized. It shows that the fs-laser direct writing technology has great advantages in the fabrication of various fiber structures with excellent properties. Furthermore, the applications of these RI-modified fiber-optic structures in sensors, lasers, birefringence adjustable elements, and couplers are also dis-cussed. To conclude, the performances of RI-modified structures and their applications are presented and compared.

Automated summary

This paper reviews the latest development of fiber-optic structures based on refractive index modification under fs-laser irradiation, including processing mechanisms and various applications. The advantages of fs-laser direct writing technology in fabricating fiber structures with excellent properties are highlighted, along with discussions on the applications of these structures in sensors, lasers, birefringence adjustable elements, and couplers. Performance comparisons and applications of RI-modified structures are presented in conclusion.