Modulation-Frequency Dependence of Spatial Resolution in Optical Correlation-Domain Reflectometry
Abstract
The spatial resolution of optical correlation-domain reflectometry (OCDR) has conventionally been described by an expression that is independent of the modulation frequency fm, source linewidth δν, and receiver resolution bandwidth (RBW). However, our previous measurements showed that the spatial resolution Δz improves with increasing fm. 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 fm, Δz decreases approximately in proportion to 1/fm, with the proportionality determined by the combined source and receiver spectral response. At high fm, 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.
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BibTeX
@misc{motoda2026modulationfrequency,
title = {{Modulation-Frequency Dependence of Spatial Resolution in Optical Correlation-Domain Reflectometry}},
author = {Keisuke Motoda and Takaki Kiyozumi and Yosuke Mizuno},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.04818},
eprint = {2609.04818},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.04818},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Modulation-Frequency Dependence of Spatial Resolution in Optical Correlation-Domain Reflectometry
AU - Keisuke Motoda
AU - Takaki Kiyozumi
AU - Yosuke Mizuno
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2609.04818
UR - https://arxiv.org/abs/2609.04818
AB - 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.
ER -