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 was inserted
and quenched between two ends of silica glass optical fibers to form a
optical coupling structure, whose length was several hundred um.
Dispite the large gap of thermal expansion coefficient between these
glass materials, neither fracture nor bubbles were observed, which
usually lead to a large optical propagation loss. The insertion loss
was less than 10 dB, which was mainly due to the lack of an optical
waveguide structure in the tellurite glass segment. Further loss
decrease is expected to be possible by introducing a refractive index
modulation.