Ultra-Long Reach 4 × 100 Gb/s Unrepeatered Transmissions With Real-Time Signal Processing Using Large Aeff Ultra-Low Loss Fiber

This paper describes the enabling fiber and amplifier technologies for ultra-long reach unrepeatered transmission submarine cable systems. The key enabling technologies include the large-area ultra-low attenuation fibers, high-efficient Remote Optically Pumped Amplifier (ROPA), and second order pumped distributed Raman amplification. The benefits of the technologies are illustrated, and their physical limiting factors for unrepeatered transmission are discussed. We then present the design and experimental demonstrations of ultra-long reach total capacity of 400 Gb/s (4 × 100 Gb/s) unrepeatered transmission links with real-time signal processing. The unrepeatered transmissions are achieved by using commercially available large-area ultra-low attenuation fibers and transceiver modules. This 4 × 100 Gb/s unrepeatered transmission over 557 km fiber is demonstrated with single fiber configuration. TeraWave SCUBA150 fibers with an effective area of 153 μm
²
and an average attenuation of 0.153 dB/km at 1550 nm, and forward and backward ROPAs with second-order Raman pumping schemes are employed in this demonstration. Long-term real-time error free transmission results are also reported. In addition, we report the experimental demonstration of real-time transmission of 4 × 100 Gb/s unrepeatered link over 578 km fiber by employing an additional dedicated pump fiber path.