Large Area Ultra Low Loss Fibre is an optical fiber engineered with an enlarged effective core area and minimized attenuation to support high-capacity signal transmission over long distances. The larger mode field diameter reduces nonlinear effects such as self-phase modulation and four-wave mixing, while ultra low loss materials and fabrication techniques limit signal attenuation. It is used in long-haul telecommunications, high-power transmission, and advanced optical sensing systems requiring extended reach and signal integrity.
We report a record long 200.6 km distributed acoustic sensing (DAS) link without inline ampli-fication, 28.6% improvement of sensing range has been achieved by using three segments of enhanced-scattering fibre (ESF) with progressively higher scattering enhancements.
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.