Low-loss few-mode fiber

Abstract

A low-loss few-mode fiber relates to the technical field of optical communications and related sensing devices, and includes, from inside to outside, a core layer (), a fluorine-doped quartz inner cladding (), a fluorine-doped quartz second core layer (), a fluorine-doped quartz depressed cladding () and a fluorine-doped quartz outer cladding (); germanium element is not doped within the core layer (), the refractive index of the core layer () is in gradient distribution, and the distribution is a power-exponent distribution; the maximum value of difference in relative refractive index between the core layer () and the fluorine-doped quartz inner cladding () is 0.3% to 0.9%; the relative refractive index difference of the fluorine-doped quartz inner cladding () with respect to synthetic quartz is −0.3% to −0.5%; the difference in relative refractive index between the fluorine-doped quartz second core layer () and the fluorine-doped quartz inner cladding () is 0.05% to 0.2%; the difference in relative refractive index between the fluorine-doped quartz depressed cladding () and the fluorine-doped quartz inner cladding () is −0.1% to −0.5%; the relative refractive index difference of the fluorine-doped quartz outer cladding () with respect to synthetic quartz is −0.3% to −0.5%. The transmission loss of optical signals of the linear polarization modes that are supported by the few-mode fiber and the relay cost are reduced.