通过将单芯单模光纤与双芯单模光纤熔接后在熔点处进行熔融拉锥，实现了单芯光纤到双芯光纤的功率耦合，解决了由于双芯光纤特殊结构引起的与光源、单芯光纤等直接耦合及监测所存在的问题。对单芯单模光纤与双芯单模光纤的耦合理论进行了研究，基于直接耦合理论与弱耦合理论建立了单芯单模光纤与双芯单模光纤的耦合方程，并就影响耦合光功率的因素进行了讨论。结果表明该理论分析方法能够有效地描写单芯光纤与双芯光纤耦合过程中光波的行为特征。

By fused biconical tapering at the fusion point of single mode single-core fiber and single mode twin-core fiber, a power tapered fiber coupling technique is implemented. The difficulties in direct-coupling with light source and single made fiber and signal detection in the two cores due to its special structure are solved. The analysis about the coupling theory of single mode single-core fiber and single mode twin-core fiber is given. With the combination of direct-coupling and weakly coupled-mode theory, the coupling equations of single mode single-core fiber and single mode twin-core fiber are proposed. The factors which influence the coupling power are also discussed. This theory analysis can explain the coupling character effectively.