Nokia Sets Data Speed Record

Introduction

The demand for bandwidth keeps growing in our digital age. One of the biggest trends in the telecom industry is to transition to higher symbol rates through integrated optics. The idea is to use high symbol rate systems to increase the aggregate per-wavelength information rate and reduce component count, cost, and power consumption.

Nokia Bell Labs is Nokia’s industrial research lab, where researchers innovate with purpose, pursuing responsible and sustainable technologies that will demonstrably impact society. Nokia Bell Labs researchers have overcome some of the world’s biggest scientific challenges. Network fundamentals are one of four key areas the researchers are studying, and that will define networking for decades  to come.

This case study will tell the story of the collaboration between Nokia and Keysight that achieved a  260 Giga Baud (GBaud) coherent data transmission record.

The Challenge: Faster transmission

A key component in advanced high-speed coherentsystems is the digital-to-analog converter (DAC). The DAC generates high-speed multi-level signals, but it is challenging to increase bandwidth above 65 GHz without sacrificing resolution and output swing. Going beyond 130 GBaud requires more than one DAC per dimension.

The Mach-Zehnder modulator (MZM) is another critical component of high-speed coherent systems. You can build the MZM using high-bandwidth technologies like thin-film lithium niobate (TFLN) modulators.

The previous record of 220 GBaud used the signaling of a 256 GSa/s arbitrary wavelength generator (AWG) and a > 50 GHz 6-dB bandwidth gallium arsenide (GaAs) I/Q modulator. However, the configuration required nonlinear digital signal processing (DSP) and the use of a maximum likelihood sequence estimator (MLSE) to compensate for the highly limited bandwidth. This approach is not desirable because it adds to system complexity.

As a leader in networking innovation, Nokia continues to push boundaries in order to achieve better, more efficient wireless and optical systems. As part of its pursuit of faster transmission, Nokia collaborates with research partners that also seek to improve network performance and efficiency.

The Solution: M8199B AWG + TFLN I/Q

The Keysight-Nokia collaboration focuses on Nokia’s pursuit of faster transmission and Keysight’s new AWG. Keysight invited Nokia to Keysight’s lab in Germany for an experiment to see whether the new AWG could push the speed of data transmission beyond 220 GBaud.

The experiment setup in the image below consists of Keysight's new 260 GSa/s AWG and a TFLN I/Q modulator, respectively, delivering more than 75 GHz and 110 GHz of bandwidth. The AWG’s and TFLN I/Q’s modulator-wide bandwidth enables the transmission of symbol rates up to 260 GBaud without using nonlinear DSP or MLSE. The results also show that net bitrates greater than 2 Tbit/s are achievable in coherent optical communications.

The Result: First 260 GBaud Record

Nokia Bell Labs and Keysight, along with the combined expertise of other research partners, provided the record-breaking demonstration of 260 GBaud dual polarization quadrature phase shift keying (DP-QPSK) coherent transmission over 100 km of standard single mode fiber (SSMF).

“Keysight is honored to work with Nokia Bell Labs on achieving 260 GBaud,” said Dr. Joachim Peerlings, vice president of Network and Data Center Solutions at Keysight. “The continued proliferation of AI requires new levels of server and network performance that must scale computing resources within reasonable energy bounds. Higher data rates and new modulation formats will be among the enabling technologies for the industry.”

“We achieved this outstanding record of maximum symbol rate of 260 GBaud by leveraging enabling technologies and the expertise of several partners,” said Haïk Mardoyan, senior research scientist at Nokia Bell Labs. “This result is a first milestone to scale long-haul data transport systems beyond  2 Tbit/s per wavelength. Improving the energy efficiency of transponders is a permanent challenge for the industry.”