Comprehensive Analysis of Longitudinal Power Monitoring in Various Fiber Types

In this paper, we show that the performance of longitudinal optical power monitoring (LPM) remains consistent across different fiber types and a wide range of wavelengths. LPM is a location-resolved monitoring method for optical transmission systems that utilizes digital signal processing (DSP) at coherent receivers to estimate distributed optical power along transmission links based on fiber nonlinear effects, without requiring additional hardware. In this study, we analyze the performance of LPM through both experimental and theoretical approaches. In our experiments, the estimation accuracy of LPM was quantitatively assessed across different fiber types and a wide range of launch powers. To investigate the impact of fiber characteristics— especially the nonlinear coefficient—on LPM performance, we conducted experiments on fiber links composed exclusively of either standard single-mode fiber or pure silica core fiber. We also conducted simulations to independently evaluate the influence of individual parameters by modeling fiber propagation with varying nonlinear coefficients. Theoretical analysis further extended the evaluation by calculating the optimal launch power and the position-wise power-profile SNR, a key performance metric of LPM, under diverse fiber parameter conditions. Experiments, simulations, and theoretical analysis showed that LPM maintains comparable estimation accuracy at the optimal launch power across various fiber types and operational wavelengths, demonstrating its robustness and applicability to future optical transmission systems.