发表机构
Faculty of Engineering, Yokohama National University; Graduate School of Engineering, The University of Tokyo; Institute for Multidisciplinary Sciences, Yokohama National University（横滨国立大学工学部; 东京大学大学院工学系研究科; 横滨国立大学综合科学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究构建带移频器的光关联域反射测量理论模型，揭示其空间分辨率随调制频率变化的两种机制，通过实验验证了该依赖性并明确其与测量范围的权衡。
AI 中文摘要
光关联域反射测量（OCDR）的空间分辨率传统上由一个与调制频率$f_m$、光源线宽$\nu$和接收机分辨率带宽（RBW）无关的表达式描述。然而，我们之前的测量显示，空间分辨率$\triangle z$随$f_m$的增大而提升。在此，我们通过评估电频谱分析仪检测到的电功率，明确纳入光源线宽$\nu$和RBW $B$，构建了带移频器的OCDR理论模型。该模型预测了两种工作机制：在低$f_m$时，$\triangle z$近似按$1/f_m$的比例减小，比例系数由光源与接收机的组合频谱响应决定；在高$f_m$时，$\triangle z$趋近于由调制幅度$\triangle f$决定的常数值，且与光源线宽和RBW滤波器无关。在RBW=1 MHz下的测量，再现了相关阶数达2048时的机制转变；在RBW=10 MHz下，频谱响应的Voigt表示法会高估$\triangle z$，而直接使用测量得到的未调制拍频谱可将偏差缩小至约10%至20%。这些结果定量描述了OCDR空间分辨率的调制频率依赖性，明确了其与测量范围的权衡关系。
英文摘要
The spatial resolution of optical correlation-domain reflectometry (OCDR) has conventionally been described by an expression that is independent of the modulation frequency $f_m$, source linewidth $δν$, and receiver resolution bandwidth (RBW). However, our previous measurements showed that the spatial resolution $Δz$ improves with increasing $f_m$. Here, we develop a theoretical model for OCDR with a frequency shifter by evaluating the electrical power detected by an electrical spectrum analyzer and explicitly including $δν$ and the RBW $B$. The model predicts two regimes. At low $f_m$, $Δz$ decreases approximately in proportion to $1/f_m$, with the proportionality determined by the combined source and receiver spectral response. At high $f_m$, $Δz$ approaches a constant value determined by the modulation amplitude $Δf$ and independent of the source linewidth and RBW filter. Measurements at RBW = 1 MHz reproduced the transition between these regimes over correlation orders up to 2048. At RBW = 10 MHz, a Voigt representation of the spectral response overestimated $Δz$, whereas direct use of the measured unmodulated beat spectrum reduced the discrepancy to approximately 10 to 20%. These results provide a quantitative description of the modulation-frequency dependence of OCDR spatial resolution and clarify its trade-off with measurement range.
Comments18 pages, 5 figures, 3 tables
