Location-resolved PDL Monitoring with Rx-side Digital Signal Processing in Multi-span Optical Transmission System

Abstract

We propose a novel monitoring that enables to localize PDL in multi-span transmission using only Rx-side DSP and experimentally demonstrate sufficient accuracy within error of 1km with eighty-two polarization combinations in three-span, 180-km transmission line.

Advanced DSP-Based Monitoring for Spatially Resolved and Wavelength-Dependent Amplifier Gain Estimation and Fault Location in C+L-Band Systems

“…Recently, several link properties, such as longitudinal power evolution [7]- [12], frequency response of bandpass filters [12], span-wise chromatic dispersion mapping [13], Raman gain [14], and polarization-dependent loss profile [15] have been obtained through Rx-DSP. In general terms, the basic principle that permits the extraction of these physical properties is the fact that the optical link can be analytically modeled using conventional split-step Fourier method.…”

“…For the Volterra DPD, we used a truncated, timeinvariant 3rd-order Volterra filter with 256 taps in the first order, and 9 taps in the second and third orders. In the sequence, this DPD filter is applied on a 64-GBd DP-16-QAM signal generated with a 2 15 pseudo-random bit sequence and shaped with a root-raised cosine pulse filter (roll-off factor 0.1). In addition to the DPD, a chromatic dispersion pre-compensation of 800 ps/nm was also performed on the transmitter side and added to the signal, as suggested in [8].…”

“…Caio Santos, Robert Emmerich, Behnam Shariati, Colja Schubert, Johannes K. Fischer and Ronald Freund are with the Fraunhofer receiver (Rx) based digital signal processing (DSP) methods have been extensively explored to estimate properties of optical fiber links [7]- [17], thus relaxing the demanding requirements of deploying multiple and expensive node-level measurement devices. Thanks to their capability in unveiling multi-span link characteristics, such as longitudinal power evolution [7]- [12], frequency response of optical filters [12], chromatic dispersion mapping [13], Raman gain [14], and polarization-dependent loss [15], these Rx-DSP monitoring methods have gained a momentum over the past few years. One successful example of Rx-DSP for estimation of link properties was demonstrated in [8], the so-called in-situ power profile estimator (PPE).…”

“…This visualization was denominated in [16] as link tomography and can be considered as a first step towards the design of a networkwide tomography [7]. In order to calculate the correlation between Tributary 1 and 2, we have used data processing blocks of 2 15 samples (32768 samples), which is a longer window than the 2 11 samples used in [9]. Although this makes the algorithm slower, given the higher number of samples to be processed, we noticed that, in turn, a reduced number of averagings could be applied to achieve a rather smooth longitudinal power estimation curve.…”

Performance Limit of Fiber-Longitudinal Power Profile Estimation Methods

“…(ii) No probing light or additional optical components are required. (iii) it has more applications such as span-wise CD map estimation [6], [7], spatial and spectral PPE [6], [11]- [14], localization of anomaly amplifiers [6], [11]- [14], anomaly filters with a detuned center frequency [6], [15], polarization-dependent loss [16], and multi-path interference [9]. PPE, therefore, has the potential to revolutionize hardware-based approaches, unveiling the physical parameter distributions of various link components and even localizing their soft failures at a coherent receiver.…”