We show strong effects of width of the launch beam’s angular distribution on bandwidth and mode coupling in W-type plastic optical fibers (POFs). In general, the broader this width, the stronger the coupling and the lower the bandwidth—but the bandwidth drop due to this effect tapers off with distance from the input end and ceases at lengths over 25 m as the steady state distribution is reached. With increasing the strength of mode coupling, the equilibrium mode distribution is reached at shorter fiber lengths, which results in slower bandwidth decrease and finally in higher bandwidth at longer fiber lengths for fibers with larger coupling coefficients D. These results are aimed at aiding designers and application integrators of W-type POFs, particularly in employing laser, LED or vertical cavity surface emitting laser (VCSEL) light source.

我们展示了发射光束角分布的宽度对 W 型塑料光纤 (POF) 中的带宽和模式耦合的强烈影响。通常，此宽度越宽，耦合越强，带宽越低，但由于这种效应导致的带宽下降随着与输入端的距离而逐渐减小，并在达到稳态分布时在长度超过 25 m 时停止。随着模式耦合强度的增加，在较短的光纤长度处达到平衡模式分布，这导致带宽下降较慢，最终对于耦合系数D较大的光纤，在较长的光纤长度处获得更高的带宽. 这些结果旨在帮助 W 型 POF 的设计人员和应用集成商，特别是在采用激光、LED 或垂直腔面发射激光器 (VCSEL) 光源方面。