High-speed free-space data transmission improves connectivity for space missions. Researchers at ETH Zurich have used plasmonic modulators to achieve record-breaking data transfer speeds, promising a boost for space communications and potentially global high-speed internet access. The transmission speed of this technology may reach 1.4Tbit/s, which will change the way the world is connected.

The scientists used plasmonic modulators - devices that use special light waves called surface plasmon polaritons to control and modify optical signals - to achieve data transfer rates of up to 424Gbit/s over a turbulent free-space optical link up to 53 kilometers (33 miles) long. The new research lays the foundation for high-speed optical communications links to transmit data in the open air or in space.

Compared with traditional radio frequency communication systems, free-space optical communication networks can provide high-speed, high-capacity data transmission with lower latency and less interference, thus benefiting space exploration. This will increase data transfer efficiency, improve connectivity, and enhance the capabilities of space missions.

Laurenz Kulmer from the Leuthold group at ETH Zurich presented the research at the Frontiers in Optics and Laser Science (FiOLS) conference.

"High-speed free-space transmission is an option to connect the world and serve as a backup if underwater cables break," said Coulmer. "But it's also a step toward a new, affordable, high-speed Internet that connects the world. In this way, it can provide stable, high-speed Internet to millions of people who are currently not connected to the Internet."


Experimental setup for FSO outdoor experiments. Tunable laser source (TLS), driving amplifier (DA), arbitrary waveform generator (AWG), transmitter digital signal processor (Tx-DSP), erbium-doped fiber amplifier (EDFA), band-pass filter (BPF), optical spectrum analyzer (OSA), polarization division multiplexing simulator (PDM), high power Optical amplifier (HPOA), real-time controller (RTC), deformable mirror (DFM), wavefront sensor (WFS), optical power meter (OPM), local oscillator (LO), balanced photodetector (BPD), digital storage oscilloscope (DSO), receiver digital signal processing (Rx-DSP). Source: Laurenz Kulmer, ETH Zurich

Plasma modulators are ideal for space communications links because they are compact and can operate at high speeds with low energy consumption over a wide temperature range.

In outdoor experiments with free-space optics, the researchers achieved information transfer rates of up to 424Gbit/s, below the 25% SDFEC threshold - a threshold under which the system can repair errors in transmitted data despite interference or noise. Experiments using a plasmonic IQ modulator in a standard fiber optic system achieved higher throughput, up to 774Gbit/s/pol, while remaining below the 25% SDFEC threshold.

Based on these results, the researchers say that combining plasmonic modulators with coherent free-space optical communications could help increase overall throughput, potentially reaching speeds of 1.4Tbit/s. The results also show that operating free-space optical links at the highest speeds is more advantageous than using higher-order modulation formats and lower-speed links. The researchers say that with further improvements in device design and photonic integration, polarization-multiplexed data transmission rates in excess of 1Tbit/s per polarization channel should be feasible.

"Next step, we will test the long-term reliability of our equipment," Coulmer said. "The high-speed performance is already there, but we have to ensure they can operate for many years in the harshest environment - space."

Compiled from/SciTechDaily