Preparation Of Novel Functional Fiber Based On Melt-in-Tube Method

In the past several years,the research of novel functional fibers has undergone a rapid development stage.For example,the glass fibers with superior broadband and high gain,the semiconductor fibers with various photoelectric properties,polymer composite fibers with composite structure and function have been successfully developed.As a typical widely applied approach for fiber fabrication,melt-in-tube?MIT?method has greatly promoted the development of new functional fiber.However,the research on the fibers fabricated under extreme condition and the diffusion between fiber core and cladding are rare.In this work,we have fabricated three kinds of crystal derived fiber?YVO₄,KNb O₃ and Cr:Ga₂O₃?using the MIT method.The constructed fibers exhibit the gradient configuration and show special optical response.This is resulted from the diffusion between the core and cladding region in fiber.This work provides a new reference for construction of novel functional fiber.The main results of this work are summarized as follows:?1?YVO₄ crystal derived fibers have been fabricated by MIT method.The fibers remain perfect core-clad configurations with relatively large transmission loss.The element and Raman spectra analysis demonstrate the obvious diffusion between the fiber core and cladding.The fiber core is composed of amorphous YVO₄ and Si O₂.Fully and space-selectively crystallized YVO₄ glass-ceramic fiber can be fabricated based on the heat-treatment and continuous laser irradiation.?2?KNb O₃ crystal derived fibers have been fabricated by MIT method.The obtained fiber core is in glass form and composed of Nb₂O₅ and Si O₂.In the precursor fiber,the[Nb O₆]units are mainly concentrated in fiber core region and sparsely distributed in the interface region between fiber core and cladding,resulted from the thermal driven diffusion.The concentration quenching leads to an unusual annular luminescence of the obtained fiber.Furthermore,the elemental gradient and annual luminescence of the fiber can be improved after heat-treatment.The potential application of the gradient fiber for infrared laser alignment has been demonstrated based on the annular luminescence.?3?Cr-doped Ga₂O₃ ceramic derived fibers have been fabricated by MIT method.The fibers remain perfect core-cladding configurations with the typical size close to single mode fiber.The structural analysis demonstrates that some Si O₂ are diffused to the fiber core region and the derived fiber is composed of Si O₂ and Ga₂O₃.The fiber exhibits good optical transmission and detectable luminescence in the 650?900 nm waveband region.It can be ascribed to the the electronic transitions of Cr³⁺.Because of the diffusion between fiber core and cladding,the Ga and Si element exhibits gradient distribution in fiber core region.Under excitation with ultraviolet light,the obtained fiber presents annular multicolor luminescence.The phenomenon might be associated with the precipitation of the Ga₂O₃ nanostructure at the interface between the fiber core and cladding,which results in the improvement of annular multicolor luminescence.