#waveguides

Carbon nanotube 'black paint' absorbs terahertz radiation to cut 6G interference

Skoltech researchers and their colleagues from KTH Royal Institute of Technology, Sweden, have created an important building block for future 6G communication technology, which will make wireless data transfer at superior transmission rates possible. The newly developed piece of the 6G puzzle is not a device component, but a carbon nanotube-based black paint of sorts that thoroughly absorbs electromagnetic radiation wherever its transmission would be detrimental. The study was published in Nature Communications. Occupying the middle ground between infrared light used in night vision and microwaves used to heat your lunch, terahertz radiation is a promising band of electromagnetic waves for 6G communication, advanced biomedical imaging and sensing.

Ocean waves can be dangerous for boats, particularly when operating near off-shore platforms. But a new study, inspired by electromagnetic waveguides, demonstrates a lab-scale water waveguide capable of damping out a range of waves experienced by any ship inside its protected area. The water waveguide sits below the surface, changing the water depth and therefore the propagation of surface waves. 

Building Better Bridges on Quantum Chips

Fabricating some structures using niobium instead of aluminum could lead to more resilient superconducting quantum computers. [...] As superconducting quantum computers become larger and more complex, it gets harder to arrange the waveguides and capacitors that are used to control and stabilize the qubits. One solution to the problem is to lift these components above the rest of the chip. Niklas Bruckmoser and Leon Koch at the Technical University of Munich and their colleagues have now demonstrated a fabrication approach that enhances these elevated structures [1].

RGB multiplexer based on lithium niobate enables faster, more efficient light modulation for laser beam scanning

As technology advances, photonic systems are gaining ground over traditional electronics, using light to transmit and process information more efficiently. One such optical system is laser beam scanning (LBS), where laser beams are rapidly steered to scan, sense, or display information. This technology is used in applications ranging from barcode scanners at grocery stores to laser projectors in light shows. To process a wider range of signals or enable full-color output, these systems utilize multiplexers that merge the red, green, and blue (RGB) laser beams into a single beam. Traditionally, this was achieved by directly modulating each laser, turning them on and off to control the output. However, this approach is relatively slow and energy intensive. A recent study by researchers at the TDK Corporation (Japan) reports the development of a faster and more energy-efficient RGB multiplexer based on thin-film lithium niobate (TFLN).

Stretchable waveguides maintain stable transmission even when bent or twisted

Researchers have designed and demonstrated stretchable waveguides that maintain efficient, stable signal transmission of surface plasmon polaritons even when bent, twisted or stretched. These plasmonic waveguides could make it possible to seamlessly embed advanced sensing, communication and health monitoring functions into everyday wearable materials. Plasmonic waveguides are tiny structures that guide light by coupling it with electrons on a metal surface. The new flexible waveguides transmit what are known as spoof surface plasmon polaritons, which are formed with longer wavelengths—radio frequencies in this case—rather than the conventional infrared or visible light. "Although our work is still at the research stage, it highlights the exciting possibility of merging advanced electromagnetic technologies with soft, stretchable materials," said research team leader Zuojia Wang from Zhejiang University. "This brings us closer to a future where advanced health care and connectivity are integrated into what we wear."

Quantum emitter discovery in diamonds enables a new type of coupling

Researchers at The City College of New York have shown how a quantum emitter, the nitrogen-vacancy (NV) center in diamond, interacts in unexpected ways with a specially engineered photonic structure when moved around with a scanning tip. The study, led by Carlos A. Meriles—Martin and Michele Cohen Professor of Physics in the Division of Science—and titled "Emission of Nitrogen–Vacancy Centres in Diamond Shaped by Topological Photonic Waveguide Modes," appears in the journal Nature Nanotechnology. What has long been considered a drawback of the NV center—its broad and messy emission spectrum—turns out to enable a new type of coupling that reshapes its light in ways not seen before. This discovery has fundamental importance for quantum information technologies, since such coupling could help overcome longstanding challenges like spectral diffusion and open pathways toward robust spin–photon and spin–spin entanglement on a chip.

Using sound waves to create a smart T-shirt

Imagine wearing a T-shirt that measures your breathing or gloves that translate your hand movements into commands for your computer. Researchers at ETH Zurich, led by Daniel Ahmed, Professor of Acoustic Robotics for Life Sciences and Healthcare, have laid the foundations for just such smart textiles. Unlike many previous developments in this area, which usually use electronics, the ETH researchers rely on acoustic waves passed through glass fibers. This makes the measurements more precise and the textiles lighter, more breathable and easier to wash. "They are also inexpensive because we use readily available materials, and the power consumption is very low," says Ahmed.

Polymer waveguides show promise for reliable, high-capacity optical communication

Co-packaged optics (CPO) technology can integrate photonic integrated circuits (PICs) with electronic integrated circuits (EICs) like CPUs and GPUs on a single platform. This advanced technology has immense potential to improve data transmission efficiency within data centers and high-performance computing environments. CPO systems require a laser source for operation, which can be either integrated directly into the silicon photonic chips (integrated laser sources) or provided externally. While integrated laser sources allow for dense CPO integration, ensuring consistent reliability can be challenging, which may affect overall system robustness. The use of external laser sources (ELS) in CPO, in comparison, offers improved system reliability.