Physical layer authentication for fiber-optic links based on multi-wavelength chromatic dispersion fingerprints

To determine whether the physical fiber carrying an optical service has been substituted, rerouted, or spoofed, we propose a physical-layer authentication method based on multi-wavelength chromatic dispersion (CD) fingerprints. Link-specific variations in refractive-index profile, geometry, residual stress, and local microstructure produce repeatable differences in cumulative CD across multiple wavelengths. The proposed method estimates CD at N C-band wavelengths and applies reference-based standardization using statistics obtained during legitimate-link enrollment, followed by Euclidean-distance matching against templates stored in a secure template database (STDB). For a 100-km G.652D link, the calibrated decision threshold is ε = 0.3071. Receiver operating characteristic (ROC) analysis yields area under the curve (AUC) values of 0.992125, 0.999685, and 0.999999 for substitution, baseline spoofing, and rerouting attacks, respectively. Under common temperature changes from -15 to 15 °C and end-to-end spatial temperature variations from 0 to 30 °C, the legitimate-link false rejection rate (FRR) remains approximately 0.58-1.65%. Additional analyses evaluate the effects of fingerprint dimension, signal-to-noise ratio (SNR), fiber length, and practical CD-estimation impairments. The method can reuse CD-estimation functions in coherent-receiver digital signal processing (DSP), providing a complementary physical-layer link-authentication mechanism for optical networks.