塑料光纤微分模延迟的频域相移法研究

Differential Mode Delay in POF Measured by Frequency-Domain Phase-Shift Technique

塑料光纤的微分模延迟数据对研究塑料光纤的色散特性具有非常重要的意义。采用频域相移法测量了不同长度的两种折射率分布塑料光纤 :阶跃型塑料光纤 (SI POF)和渐变型塑料光纤 (GI POF)的微分模延迟曲线。实验结果表明 ,由于短光纤可以忽略模式耦合和模式损耗 ,1m塑料光纤的微分模延迟测量值与理论计算值吻合得非常好。因此 ,频域相移法可以简单、方便、精确地测量塑料光纤的微分模延迟。此外 ,通过比较不同长度塑料光纤的微分模延迟曲线的变化 ,可在一定程度上分析光纤中存在的模式耦合。

Knowledge of differential mode delay data of polymer optical fiber plays an important role in studying the dispersion characteristic of the fiber. Differential mode delay of step index-polymer optical fiber (SI-POF) and gradient index-polymer optical fiber (GI-POF) with various lengths is measured by the frequency-domain phase-shift technique. Due to the fact that the mode coupling and the mode-dependent loss can be neglected for short fibers, the measured values of the differential mode delay for the 1 m fibers agree well with the theoretical ones. Therefore, the frequency-domain phase-shift technique provides a simple, convenient way to determine the differential mode delay of the polymer fibers with high accuracy. In addition, the mode coupling of POF can be analyzed to some extent by comparing the differential mode delay curves of the fibers with various lengths.