高分光比光纤零耦合器临界耦合特性的理论分析与实验论证

Experimental and Theoretical Study on the Critical-coupling Characteristic of Fiber Null Coupler with High Splitting Ratio

对光纤失配非对称耦合器中的模式耦合特性进行了理论和实验研究 ,给出了两光纤失配量的临界判据r2 r1 =0 62～ 0 63 ,指出当失配度超过此下限后 ,因出现高阶模的耦合而降低分光比。合理控制失配量 ,研制出分光比为 5× 10 3～ 10 5,损耗为 0 1～ 0 .2dB的光纤零耦合器。

The mode coupling characteristic in the asymmetrical coupler is studied theoretically and experimentally. The critical fiber-mismatch criterion of r2/r1=0.62-0.63 is given. It is shown that when the fiber mismatch exceeds the limit, higher order mode coupling occurs and the splitting ratio decreases. By controlling the fiber mismatch properly, the fiber null coupler with splitting ratio of 5×103-105 and loss of 0.1-0.2 dB is made.