image: Fig. 1 Experimental setup of the FSO outdoor experiments. Tunable laser source (TLS), driving amplifier (DA), arbitrary waveform generator (AWG), transmitter digital signal processing (Tx-DSP), erbium-doped fiber amplifier (EDFA), bandpass filter (BPF), optical spectrum analyzer (OSA), polarization division multiplexing emulator (PDM), high power optical amplifier (HPOA), real time controller (RTC), deformable mirror (DFM), wafefront sensor (WFS), optical power meter (OPM), local oscillator (LO), balanced photodetector (BPD), digital storage oscilloscope (DSO), receiver digital signal processing (Rx-DSP)
Credit: Laurenz Kulmer, ETH Zurich
Researchers have achieved data rates as high as 424Gbit/s across a 53-km turbulent free-space optical link using plasmonic modulators— devices that uses special light waves called surface plasmon polaritons to control and change optical signals. The new research lays the groundwork for high-speed optical communication links that transmit data over open air or space.
Free-space-optical communication networks could aid space exploration because they can provide high-speed, high-capacity data transmission with lower latency and less interference than traditional radio frequency communication systems. This could lead to more efficient data transfer, better connectivity and enhanced capabilities for space missions.
Laurenz Kulmer from the Leuthold group of ETH Zurich will present this research at Frontiers in Optics + Laser Science (FiO LS), which will be held 23 – 26 September 2024 at the Colorado Convention Center in Denver.
“High-speed free-space transmission is an option to connect the world, or it may serve as a backup if underwater cables break,” said Kulmer. “Nevertheless, it is also a step towards a new cheap high-speed internet that may connect all locations across the world. This way it may contribute towards a stable, high-speed internet for millions of people who are currently unconnected.”
Plasmonic modulators are ideal for space communication links because they are compact while also operating at high speeds over a wide temperature range with low energy consumption.
In free-space optical outdoor experiments, the researchers achieved information rates of up to 424 Gbit/s below a 25% SD FEC threshold — the point at which a system can still fix errors in transmitted data despite interference or noise. Experiments using a plasmonic IQ modulator in a standard fiber system achieved an even higher throughput of up to 774 Gbit/s/pol while staying below a 25% SD FEC threshold.
Based on these results, the researchers say that combining plasmonic modulators with coherent free-space optical communication could help increase overall throughput, with speeds potentially reaching 1.4 Tbit/s. The findings also show that it is favorable to operate free-space optical links at the highest speeds, rather than using higher order modulation formats and low speeds. With additional improvements in device design and photonic integration, the researchers say it should be feasible to reach polarization multiplexing data rates above 1 Tbit/s for each polarization channel.
“In a next step we are going to test the long-term reliability of our devices,” said Kulmer. “High-speed performance has been shown, but we have to make sure they can operate for years to come in the harshest of environments, space.”
About Frontiers in Optics + Laser Science
Frontiers in Optics, the annual meeting for Optica is presented with Laser Science, the annual meeting of the American Physical Society, Division of Laser Science. The two meetings unite communities from both societies for comprehensive and current research in a diverse collection of optics and photonics topics and across the disciplines of physics, biology and chemistry. The 2024 FiO LS Conference will feature hundreds of live contributed and invited talks. More information at https://www.frontiersinoptics.com.
About Optica
Optica, Advancing Optics and Photonics Worldwide, is the society dedicated to promoting the generation, application, archiving and dissemination of knowledge in the field. Founded in 1916, it is the leading organization for scientists, engineers, business professionals, students and others interested in the science of light. Optica's renowned publications, meetings, online resources and in-person activities fuel discoveries, shape real-life applications and accelerate scientific, technical and educational achievement. Discover more at: Optica.org