光纤生物传感器探针锥形设计及参数优化

The Taper Design and Parameter Optimication of Fiber Optical Evanescent Wave Bisosensor

对免疫型光纤生物传感器的关键部件——光纤探针进行了分析。以模式匹配理论计算出的匹配半径为基础,采用图解法分析激发光在锥型光纤探头中的光线传输轨迹。根据倏逝波透射深度与光线入射角之间的关系,结合不同形状的探针内面对光线反射角的影响,提出抛物线锥形光纤探头,并对抛物线参数进行了比较。计算结果表明,为使入射光在均匀感应部分激发的能量最大,入射角在锥形感应部分必须满足在锥形终端最小且刚好是临界角的条件。通过对抛物线参数的选择,在锥形过渡段入射角在满足全反射的同时更接近于临界角,从而激发出更大的倏逝波,并与实验结果较好地符合。

This article analyzes the most essential part of fiber biosensor, fiber probe. Based on matching radius of fiber probe obtained according to the theory in given conditions, the exciting light transmission track in the probe of linear taper is analyzed. According to the relationship between the penetration depth of the evanescent wave and the incident light angle, with the inner face kf probe to the effect of the light reflection angle,a new parabola taper fiber is put forward and compared with different tapers. The result shows that to make the energy excited at uniform sensitive part maximum, incident angle must be minimal at the end of taper and equal to critical angle. By selecting proper parameter of parabola, incident angle is closer to the critical angle at the taper transition phase when it＇s still larger than the critical angle, and better penetration depth is achieved. In the end, theoretical result matches with experiment well.