Nanowerk April 22, 2023 Polarization conversion and beam scanning metasurfaces are commonly used to reduce polarization mismatch and direct electromagnetic waves in a specific direction to improve the strength of a wireless signal. However, identifying suitable active and mechanically reconfigurable metasurfaces for polarization conversion and beam scanning is a considerable challenge, and the reported metasurfaces have narrow scanning ranges, are expensive, and cannot be independently controlled. Researchers in South Korea proposed a reconfigurable transmissive metasurface combined with a scissor and rotation actuator for independently controlling beam scanning and polarization conversion functions. They constructed metasurface with rotatable unit cells (UCs) that […]
Tag Archives: Communications technology
Could new technique for ‘curving’ light be the secret to improved wireless communication?
Science Daily April 9, 2024 A key challenge in millimeter-wave and terahertz wireless networks is blockage of the line-of-sight path between a base station and a user. A team of engineers in the US (University of Missouri-Kansas City, Rice University, Brown University) proposed a solution to this problem leveraging the fact that, in such scenarios, users are likely to be located within the electromagnetic near field of the base station, which opens the possibility to engineer wave fronts for link maintenance. They showed that curved beams, carrying data at high bit rates, could realize a link by curving around an […]
Waterproof ‘e-glove’ could help scuba divers communicate
Nanowerk April 10, 2024 Existing tactile sensing gloves fall short in terms of user comfort and are ill-suited for underwater applications. Researchers in China proposed and constructed a flexible hand gesture recognition glove (GRG) that contained high-performance micropillar tactile sensors (MPTSs) inspired by the flexible tube foot of a starfish. The sensor has a wide working range, superfast response time, reliable repeatability, and a low limit of detection and they were waterproof. When integrated with machine learning algorithm, the GRG system achieved intelligent recognition of 16 hand gestures under water, extending real-time and effective communication capabilities for divers. According to […]
100 kilometers of quantum-encrypted transfer
Phys.org April 2, 2024 Continuous-variable (CV) quantum key distribution (QKD) with coherent states and coherent detection integrates well with existing telecommunication networks. Thus far, long-distance CV-QKD has only been demonstrated using a highly complex scheme where the local oscillator is transmitted, opening security loopholes for eavesdroppers, and limiting potential applications. Researchers in Denmark have demonstrated a long-distance CV-QKD experiment with a locally generated oscillator over a 100-kilometer fiber channel with a total loss of 15.4 decibels. This was done by controlling the phase noise–induced excess noise through a machine learning framework for carrier recovery and optimizing the modulation variance. They […]
Deciphering quantum enigmas: The role of nonlocal boxes in defining the boundaries of physical feasibility
Phys.org February 14, 2024 Nonsignaling boxes (NS) are theoretical resources defined by the principle of no-faster-than-light communication. They generalize quantum correlations and some of them are known to collapse communication complexity (CC). However, this collapse is strongly believed to be unachievable in nature. An international team of researchers (France, Canada) provided intuition on which theories are unrealistic. They found a better sufficient condition for a nonlocal box to collapse CC, thus extended the known collapsing region. In some slices of NS, they showed that this condition coincides with an area outside of an ellipse… read more. TECHNICAL ARTICLE Full […]
Photonic crystals bend light as though It were under the influence of gravity
Nanowerk October 16, 2023 An international team of researchers (Japan, Spain) demonstrated electromagnetic waves following a gravitational field using a photonic crystal. They introduced spatially distorted photonic crystals (DPCs) capable of deflecting light waves owing to their pseudo gravity caused by lattice distortion. They experimentally verified the phenomenon in the terahertz range using a silicon DPC. Pseudo gravity caused by lattice distortion revealed alternative approaches to achieve on-chip trajectory control of light propagation in PCs. Their work has far-reaching implications for the world of optics and materials science, and bear significance for the development of 6G communications… read more. TECHNICAL […]
Toward metropolitan free-space quantum networks
Phys.org October 10, 2023 An international team of researchers (Germany, Austria) developed a deployable free-space QKD system and demonstrated its use in realistic scenarios. They developed and launched a low-Earth-orbit satellite for implementing decoy-state QKD—a form of QKD that uses weak coherent pulses at high channel loss and was secure because photon-number-splitting eavesdropping could be detected. They achieved a kilohertz key rate from the satellite to the ground over up to 1,200 kilometres. The key rate was around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. According to the researchers their work […]
Team develops way to integrate electro-optic modulator device on end faces of a single-mode optical fiber jumper
Phys.org August 23, 2023 Digitalizing optical signals through electric driving signals, electro-optic modulators (EOMs) are one of the cardinal elements in modern optical communications. Most of current EOM devices are targeting on-chip integrations, which routinely suffer from high coupling losses, complex optical alignments, and single-band operations. Researchers in China integrated a lumped EOM device on the end faces of a single-mode optical fiber jumper for fast amplitude modulations. Taking advantage of the ultrathin and high quality-factor plasmonic metasurfaces, nanofabrication-friendly and highly efficient EO polymers and coupling-free connections with fiber networks, the EOM was demonstrated to allow dual-band operations and high-speed […]
Limiting loss in leaky fibers
Science Daily July 3, 2023 Antiresonant, hollow-core optical fibers are currently challenging or even exceeding the loss performance of conventional solid-core fibers. Researchers in the UK have shown that the glass elements of the cladding structure with an approximately radial orientation play a crucial role in determining the confinement loss by strongly shaping the wave fields in the azimuthal coordinate. Azimuthal confinement can result in an evanescent field in the radial direction through the cladding, leading to a confinement loss that is substantially lower than would be the case without azimuthal confinement. They developed a comprehensive theory of azimuthal confinement, […]
Telecom-wavelength quantum repeater node transmits quantum information over tens of kilometers
Phys.org May 23, 2023 An international team of researchers (Austria, France) has presented a quantum repeater node based on trapped ions that act as single-photon emitters, quantum memories, and an elementary quantum processor. They demonstrated the node’s ability to establish entanglement across two 25-km-long optical fibers independently, then to swap that entanglement efficiently to extend it over both fibers. The resultant entanglement was established between telecom-wavelength photons at either end of the 50 km channel. Finally, they calculated the system improvements to allow for repeater-node chains to establish stored entanglement over 800 km at hertz rates revealing a near-term path […]