Fiber-coupler fabrication with automatic fusion-elongation processes for low excess loss and high coupling-ratio accuracy

A novel fiber-coupler fabrication system which automatically processes fusion and elongation is presented. Not only conventional single-mode fiber couplers but also polarization-maintaining fiber couplers with excellent characteristics such as excess losses less than 0.11 dB and coupling-ratio accuracy better than 1.3 percent were obtained. In addition, it was confirmed that polarization crosstalk for polarization-maintaining fiber couplers in the present system was lower than that for the conventional manual method. The fabrication yield and reliability of the present system have been much higher than those of the conventional method and the processing time for fabrication could also be reduced.