Read our Optical Networking and Sensing publications from our team of researchers. We are leading world-class research into the next generation of optical networks and sensing systems that will power ICT-based social solutions for years. We advance globally acknowledged innovation by engaging in visionary theoretical research, pioneering experiments, and leading technology field trials. Our work not only foresees the future but also transforms it into today’s reality.
Polarization-based, multi-span sensing over a link without reflection-back circuits is demonstrated experimentally. It is shown that distributed reflection from Rayleigh scattering can serveas an alternative to reflectors after spatial averaging of received state-of-polarization
Optical transmission networks require intelligent traffic adaptation and efficient spectrum usage. We present scalable machine learning (ML) methods for network performance modeling, andfield trials of distributed fiber sensing and classic optical network traffic coexistence.
Passive-Optical-Networks (PON) have emerged as a pivotal technology for broadband access network and are now expanding to wireless communication, supporting 5G and development of future 6G frameworks. PON systems are expected to find many new applications, including in electrical power grids, modern industrial factories, and smart city infrastructure. With the growing capabilities and increasing complexity and extent of the optical distribution network, effective surveillance of fiber infrastructure has become increasingly important to ensure long-term viability and dependability. Simultaneously, there is increasing demand for effective distributed monitoring systems for the power-grid elements and machinery in automated factories operating within PON environments. This paper discusses the challenges and potential solutions for implementing distributed acoustic sensing (DAS) within PON architecture. We will present design and experimental demonstrations of a co-existing DAS and 10G PON (XGS-PON) system with a 23.5 km feeder fiber (FF) and a 1 × 16 splitter. A unique signature from each distributed fiber (DF) and optical network units (ONU) is detected by utilizing a coded Enhanced Scatter Fiber (ESF). Vibration events originating from up to three DF/ONUs are identified using a novel scheme using the coded ESFs in conjunction with fiber delay lines. We further investigated the sensing performance and potential crosstalk between XGS-PON and DAS signals within this co-existing DAS and XGS-PON system.
We demonstrate a wavelength tunable Distributed-Vibration-Sensing over PON scheme using low-cost ITLA and Enhanced-Scattering-Fibers. Vibrations at frequency grids of 193.40THz and194.60THz in a PON with 1×16 splitter and 21 km feeder-fiber were successfully detected.
Publication Date: 6/29/2025 Event: OECC/PSC 2025 Reference: WC2-1: 1-3, 2025 Authors: Paul S. Westbrook, OFS Labs; Benyuan Zhu, OFS Labs; Kenneth S. Feder, OFS Labs; Zhou Shi, OFS Labs; Tristan Kremp, OFS Labs; Yaowen Li, NEC Laboratories America, Inc.; Ting Wang, NEC Laboratories America, Inc.; David J. DiGiovanni, OFS Labs Abstract: We discuss recent advances […]
Subsea cables include a supervisory system that monitors the health of the amplifier pumps and fiber loss on per span basis. In some of the cables, the monitoring is achieved optically and passively using high-loss loop back paths and wavelength selective reflectors. By sending monitoring pulses through the supervisory channel and comparing the phases and polarizations of the returning pulses reflected by consecutive reflectors, dynamic disturbances affecting individual spans can be monitored on a per span basis. Such per-span phase monitoring techniques require high phase coherence compared to DAS systems since the spans are 10s of kms long compared to typical DAS resolution of meters. A time-frequency spread technique was demonstrated to limit the coherence length requirement, however the limits of its effectiveness was not quantified. In this paper we present a detailed analysis of the trade-off between implementation complexity and the phase noise tolerance for given span length by lab experiments.
We present a simple and accurate semi-analytical model predicting the gain of a single-stage erbium-doped fiber amplifier (EDFA) embedded with an unknown gain flattening filter (GFF). Characteristic wavelength-dependent gain coefficients and their scaling laws are extracted with a limited set of simple flat input spectrum measurements at variable temperatures and pump powers. Based on a black box approach, the proposed model provides a precise gain profile estimation of GFF-embedded EDFA for non-flat input spectra in variable temperature and pump power conditions. The accuracy of the presented methodology is validated on an extensive experimental dataset and compared with state-of-the-art gain models based on semi-analytic and solutions.
We present techniques to extend the sensing range in unrepeatered submarine cable systems by utilizing Enhanced-Scattering Fibre (ESF), large-area ultra-low-loss (ULL) fibre, and a digital Distributed Acoustic Sensing (DAS) interrogator. A DAS sensing range of up to 200.6 km has been achieved using 156km SCUBA125 fibre, followed by three segments of ESF. Additionally, we demonstrate long-range sensing capabilities and high-capacity data transmission over a 270.6 km unrepeatered submarine system, where DAS and 400G DWDM data transmission coexist. The impact of Distributed Raman Amplification (DRA) on sensing performance, and crosstalk between DAS and 400G DWDM channels in coexistence of DAS and unrepeatered transmission system are studied. Finally, we briefly discuss the potential application scenarios for monitoring undersea cables using ESFs.
We propose a novel Distributed Fiber Optic Sensing (DFOS) placement strategy tailored to the evolving needs of modern power grids, where fiber cables serve dual purposes: communication and real-time sensing. Our approach integrates a heuristic algorithm, PURE (Power Source-aware Route Exploration), with Integer Linear Programming (ILP) to optimize DFOS placement while addressing power supply constraints. The strategy ensures resilient monitoring across diverse grid scenarios by prioritizing observability during outages and leveraging advancements in fiber infrastructure deployment. Case studies demonstrate the effectiveness of our methodology in maintaining power grid resilience while minimizing deployment costs.
A 100-meter-long fiber optic cable was installed at the bottom of a water tank at the Davidson Laboratory, together with a hydrophone for reference. The water tank is approximately 2.5 meters deep and 95 meters long; the tank also employs a 6-paddle wavemaker which can generate programmable surface waves. A 155-cm-long model boat weighing 6.5 kilograms was automatically dragged on the surface of the tank via an electrical towing mechanism. The movement of the model boat along the fiber cable and over the hydrophone was recorded using a commercially available NEC Distributed Acoustic Sensing (DAS) system and simultaneously by a hydrophone. The experiments were repeated with and without the artificially generated surface waves. The data obtained from the hydrophone and the DAS system are presented and compared. The results show the compatibility between the DAS data and the hydrophone data. More importantly, ourresults show that it is possible to measure the surface waves and to detect a surface vessel approaching the sensor by only using the time domain analysis in terms of detected total energy over time.
