By STEPHEN HARDY, Lightwave -- Nokia Bell Labs reported in a post-deadline paper at this month's OFC 2020 (yes, there were post-deadline papers delivered) that it has accomplished a single-carrier transmission of 1.52 Tbps over 80 km of standard single-mode fiber. The transmission is a world record, Nokia Bell Labs asserts, and was one of several innovations the organization described during last week’s event.
A Nokia Bell Labs optical research team led by Fred Buchali achieved the 1.52-Tbps transmission using a 128-Gsample/sec converter that enabled the generation of signals at a symbol rate of 128 Gbaud and information rates of the individual symbols beyond 6 bits/symbol/polarization. Nokia Bell Labs also held the previous record, 1.3 Tbps, set in September 2019 as part of a field trial with Etisalat.
Also at OFC 2020, Nokia Bell Labs reported the following results:
* Di Che and team set a new data-rate world record for directly modulated lasers (DMLs) of beyond 400 Gbps for links up to 15 km.
* A team led by Roland Ryf completed what is said to be the first field trial using spatial-division-multiplexed (SDM) cable over a 2,000 km span of four-core coupled-core fiber. The experiment demonstrated the technical viability of coupled-core fibers that offer high transmission performance while maintaining an industry standard 125-um cladding diameter, says the lab.
* Ryf, alongside Rene-Jean Essiambre and Murali Kodialam, also led a team that has proposed a new set of modulation formats that provide improved linear and nonlinear transmission performance at submarine distances of 10,000 km. The formats are generated by a neuronal network and can significantly outperform traditional formats (such as QPSK), the lab asserts.
* Researcher Junho Cho and team reported on an experiment that demonstrated capacity gains of 23% for submarine cable systems that operate under electrical supply power constraints. Optimization of the gain shaping filters via neural networks enabled the capacity gains.
The research above was conducted within Nokia Bell Labs’ Smart Optical Fabric & Devices Research Lab. Researchers in this lab design and build work to develop new technologies for optical communications systems through work in such avenues as physics, materials science, math, software, and optics.
STEPHEN HARDY is Editorial Director and Associate Publisher of CI&M's sister publication, Lightwave.