Formation of optical coupling structure between two ends of silica glass optical fibers by inserting tellurite glass melt

Several nano liters of tellurite glass melt (xTeO2 - (100 - x)ZnO, x = 80,90,100 in mol%) were inserted and quenched between tow ends of silica glass optical fibers to form a new optical coupling structure, whose length was several hundred microns. No visible precipitates were found even in the quenched melt of 100% TeO2. On the basis of reflection and insertion loss measurements and a bending test, it is proved that there’s no micro crystals in the quenched melt segment which cause light scattering and/or stress concentration. Few tens nano liters of the melt were also inserted into a silica glass capillary tube with the tube diameter of 125μm, in order to examine their tolerance to the residual stress induced on cooling due to the large gap in thermal expansion coefficient between the two glasses. Neither fracture nor bubbles were observed in the quenched melt inside if its length is less than 2mm. This implies that tellurite melt can be introduced into voids of sub-mm in size to integrate hybrid lightwave circuits.