Physics-guided waveform tokenization and Mamba2 for fault-aware coherent receivers.

Soft link faults in coherent optical networks can degrade service quality, motivating receiver-side monitoring methods that exploit signals already captured during operation. We experimentally demonstrate a fault-aware coherent receiver that adds a parallel monitoring branch based on physics-guided waveform tokenization (PGWT) and Mamba2 to conventional signal recovery. PGWT converts receiver waveform tensors into typed physical tokens describing local in-phase/quadrature (I/Q) statistics, envelope variation, phase-increment roughness, spectral bands, spectral shape, coupling, and global balance. The resulting 149×10 token sequence is processed by an Mamba2 selective state-space monitor. In coherent transmission experiments from 320 to 1280 km with controlled 3 and 5 dB attenuation soft faults, PGWT-Mamba2 achieves 0.9211±0.0083 macro F1 for binary attenuation detection and 0.8202±0.0302 for three-state severity estimation, with model-forward latencies of 5.37 and 5.31 µs per waveform-capture token sequence. Token evidence links the controlled soft faults to distributed phase, balance, spectral, and coupling signatures in the compensated receiver waveform.