Study On Laser Property Of Yb-Doped Gradient-Index Fiber

Gradient-index (GRIN) fiber is a novel gain fiber, in the present work, variational method is applied to strictly analysis the boundary value problems of theα-power GRIN fiber. The eigenvalue equations and the cut-off frequency formulae are obtained, at the same time a numerical solution are given.A novel Yb³⁺-doped borosilicate glass is prepared by a two-step melting process. Though measuring the density, thermal expansion coefficient, DSC, absorption spectrum, fluorescence spectrum, fluorescence lifetime and so on of the glass, its relevant properties is calculated via Judd-Ofelt and McCumber theory. As it turns out that the glass has a long fluorescence lifetime (1.47ms), large emission cross section (0.651pm²), so it's an excellent laser gain material.The GRIN glass is prepared using our borosilicate glass by ion-exchange process. Its grid imaging is studied and refractive index profile is measured. The results indicate that the glass has a good ion-exchanging property, and is an ideal candidate material of Yb³⁺-doped GRIN fiber.GRIN fiber is successfully drawn by rod-in-tube technique with our GRIN glass serving as core material. Then a series of tests and experiments are carried out on the transmission loss, fluorescence and laser properties of the fiber, the results show that our Yb³⁺-doped GRIN fiber is a high-quality novel fiber with the potential to being a "road map" to future research of high-power fiber.