Researchers from Tianjin University, together with collaborators in Singapore and the United States, have pulled off something pretty neat: they built a custom nonlinear metasurface that can generate and switch between two different skyrmion-carrying terahertz pulses. This could open a new way to encode wireless data by using the topological stability of skyrmions at terahertz frequencies—a range that could support much faster data rates than what we have now, though it’s not without its own headaches.
Overview of the metasurface and pulse shaping
The metasurface contains over five million horseshoe-shaped gold elements. Each one is about 200 nanometers wide, sitting on an 8-nanometer-thick indium tin oxide film.
By shaping an infrared laser into a ring or a radial beam and passing it through polarization optics, the team creates single-cycle, toroidal terahertz pulses with stable, vortex-like topologies. This complex nanoscale design is what lets them turn optical input into highly controlled terahertz fields, each with its own unique topological “signature.”
Ring and radial excitation determine skyrmion type
If they use a ring-shaped excitation, they get electric skyrmions—imagine magnetic doughnuts threaded by electric currents. Switch to radial excitation, and they generate magnetic skyrmions—doughnut-shaped electric currents threaded by magnetic flux.
These two states are fundamentally different topological textures in the terahertz field. That gives them a way to flip between two robust, binary-like modes that don’t easily get messed up by noise or interference.
Topological switching and verification
The team showed they could reliably switch between the two skyrmion states by rotating a half-wave plate and using a vortex half-wave retarder. They mapped out the changing pulse fields with spatiotemporal scans.
Even as they transitioned from ring to radial excitation and back, the unique topological character of the pulses held steady. That level of control—over both the topology and the timing of the pulse—is what makes this approach so tempting for future terahertz data encoding.
Why skyrmions matter for terahertz data encoding
Skyrmions are topologically stable, which makes them pretty appealing as information carriers in the terahertz range. Data rates here could leave today’s wireless standards in the dust, though the spectrum is tricky thanks to noise from the atmosphere and materials.
If you design encoding schemes around the skyrmion type, or maybe even its intensity and purity, you could build high-density, resilient communication channels. That’s a big deal for researchers and industry folks who’ve been eyeing this part of the spectrum for ages.
- Binary data could be encoded by toggling between electric-skyrmion and magnetic-skyrmion states, using two distinct topologies as information states.
- Bit rates might jump by modulating pulse intensity and topology purity, opening up multi-level encoding beyond just binary schemes.
- There’s room to explore multiplexed signaling that taps into the spatial, temporal, and topological freedom you get from skyrmion-based terahertz pulses.
Challenges and future directions
Of course, there are some real-world hurdles. The biggest headache right now is conversion efficiency—the system only turns about one out of every 100 million infrared photons into a terahertz photon. That’s not going to cut it for practical devices.
Researchers are looking at alternative emitter materials, like spintronic sources or photoconductive antennas, hoping these could boost efficiency and make the devices tougher. They’re optimistic that material engineering and device tweaks can eventually solve these problems, though they’re not making any promises about when this could hit the market.
Bottom line: a path toward topologically encoded terahertz communications
The study brings together a multi-million-element nanoantenna array and some pretty advanced light shaping. With this setup, they manage to steer the terahertz signal into two clear, stable skyrmion configurations.
If researchers can tackle challenges like conversion efficiency and long-term stability, this method might unlock new ways to encode wireless data. Topological photonics at terahertz frequencies—now that’s a direction worth watching.
Here is the source article for this story: Switchable Skyrmions Point to Terahertz Data Links