AI 中文总结
该研究针对传统光相关域反射计的范围-分辨率耦合问题，提出拍谱设计方法，采用周期伪随机调制实现100公里光纤的长距离测量与末端附近15厘米分辨率的局域探测，削弱了传统调制的耦合效应。
AI 中文摘要
基于正弦频率调制的传统光相关域反射计（OCDR）存在测量范围与空间分辨率的耦合问题，因为两者均受调制频率控制。本文针对任意周期频率调制构建了OCDR模型，并将调制波形与所得拍谱关联；通过将瞬时光频率表示为傅里叶级数，拍谱可写为各谐波分量频谱贡献的连续卷积，该模型建立了调制波形的谐波组成与空间响应的关联。实验中采用周期伪随机调制（PPRM）验证此关联：首先使用正弦调制测量约100公里光纤的全长反射率分布，随后在光纤末端附近进行基于PPRM的随机接入探测，在局域测量中成功分辨两个间距极近的反射点，相关峰宽度约为15厘米。结果表明，拍谱设计可削弱传统正弦调制OCDR的范围-分辨率耦合，实现长距离测量与局域高分辨率探测的结合。
英文摘要
Conventional optical correlation-domain reflectometry (OCDR) based on sinusoidal frequency modulation exhibits a coupling between measurement range and spatial resolution because both are governed by the modulation frequency. Here, we formulate OCDR for arbitrary periodic frequency modulation and relate the modulation waveform to the resulting beat spectrum. By expressing the instantaneous optical frequency as a Fourier series, the beat spectrum is written as successive convolutions of the spectral contributions from the harmonic components. This formulation relates the harmonic composition of the modulation waveform to the spatial response. Periodic pseudo-random modulation (PPRM) was used to test this relation experimentally. We first measured the full-length reflectivity distribution along an approximately 100-km fiber using sinusoidal modulation and then performed PPRM-based random access interrogation near the fiber end. In the local measurement, two closely spaced reflection points were resolved with a correlation-peak width of approximately 15 cm. These results show that beat-spectrum design can reduce the range-resolution coupling of conventional sinusoidal-modulation OCDR and combine long-range surveying with localized high-resolution interrogation.
