根据光纤的模式匹配理论计算了给定条件下光纤探头的模式匹配半径，以此匹配半径为基础分析了激发光在锥型光纤探头中的光线传输轨迹．结果表明，在此条件下如不对光纤探头的耦合光束进行限定，将有一部分激发光在锥型光纤探头中因不满足全反射的传输条件而透射出光纤探头，从而使传感器系统得到虚假检测信息．针对此问题，在光纤倏逝波生物传感器的系统设计中给出了具体的解决方法．

The matching radius of fiber probes with given conditions ation based on the theory of mode matching.The ray tracing of exciting laser propagation in the tapered probe with the calculated matching radius is analysed.The analyzing results indicate: if the probe coupling beams were without limitation,some rays would not satisfy the conditions of total internal reflection when they were propagated in tapered probe and would leak out the probe. In this case,the biosensor system would get false detection result and affected the system reliability. It presented this problem and resolved it in the system designing procedures.