독립적으로 분배비 가변과 위상 이동 제어가 가능한 이터븀 도핑된 광섬유 측면 가공 커플러의 개발

Abstract

In this paper, a side-polished fiber coupler was fabricated using ytterbium-doped optical fiber and its properties were measured. The fabricated side-polished fiber coupler has a variable split ratio and can perform phase shifts independently. The split ratio characteristics of the fabricated side-polished fiber couplers were similar to those of single-mode fibers. To verify the phase-shifting characteristics, a phase-shifting interferometer was constructed using the side-polished ytterbium-doped fiber coupler, and the phase-shifting characteristics were analyzed from the generated interference signals. Sufficient phase-shifting could be induced by adjusting screw to change the split ratio. From the measurement results of the phase shifts caused by the pump light while maintaining a fixed split ratio, the fabricated side-polished ytterbium-doped fiber coupler was able to induce a phase shift of about 2π. The qualitative dependence of the phase shift on the length of the ytterbium-doped optical fiber used was also confirmed. We have shown that the side-polished fiber coupler fabricated with ytterbium-doped optical fiber can arbitrarily adjust the splitting ratio and can independently control the phase shift using external pump light. The development of photonic devices that can independently control these two functions is expected to increase their usefulness in various applications.