Phys.org October 22, 2021 An international team of researchers (USA – Caltech, Japan) constructed a material from black phosphorous which has anisotropic optical properties. As the black phosphorous is a semiconductor, structures built from black phosphorous can control the polarization of light as an electric signal is applied to them. This makes it possible to make an array of these elements each of which can convert the polarization into a different reflected polarization state. A telecommunications device based on thin layers of black phosphorous could tune the polarization of each signal so that they don’t interfere with each other. This […]
Category Archives: Communications technology
New quantum transmission protocol has higher data transmission rate, robustness against interference
Phys.org September 22, 2021 One of the fundamental principles enabling entanglement-based quantum communication security is the fact that interfering with one photon will destroy entanglement and thus be detectable. However, this property is also the greatest obstacle. Random encounters of traveling photons, losses, and technical imperfections make noise an inevitable part of any quantum communication scheme, severely limiting distance, key rate, and environmental conditions in which quantum key distribution can be employed. Using photons entangled in their spatial degree of freedom, an international team of researchers (China, Austria, Canada, Czech Republic, Slovakia) has shown that the increased noise resistance of […]
Nanostructure-based lasers for information and communication technologies
Phys.org August 18, 2021 Key applications in 5G and 6G optical networks require the utilization of laser sources to perform complex tasks at ultra-fast speed and to enable broadband, secure and energy efficient communications. An international team of researchers (France, USA – University of New Mexico) reviews recent findings and prospects on nanostructure based light emitters where active region is made with quantum-dot and quantum-dash nanostructures. To link the material and fundamental properties with the device physics, they closely examined spectral linewidth, polarization anisotropy, optical nonlinearities as well as microwave, dynamic and nonlinear properties. The paper focuses on photonic devices […]
Backscatter breakthrough runs near-zero-power IoT communicators at 5G speeds everywhere
Science Daily June 25, 2021 Backscatter radio is typically limited to data rates of hundreds of megabits per second because of the low frequency bands used and the modulation techniques involved. An international team of researchers (USA – industry, Georgia Institute of Technology, UK) designed and demonstrated a millimetre-wave modulator and antenna array for backscatter communications at gigabit data rates. It consists of a microstrip patch antenna array and a single pseudomorphic high-electron-mobility transistor that supports a range of modulation formats including binary phase shift keying, quadrature phase shift keying and quadrature amplitude modulation. The circuit is additively manufactured with […]
Researchers propose the use of quantum cascade lasers to achieve private free-space communications
Phys.org June 22, 2021 An international team of researchers (France, Germany, USA – UCLA, University of New-Mexico) shows that two uni-directionally coupled quantum cascade lasers operating in the chaotic regime and the synchronization between them allow for the extraction of the information that has been camouflaged in the chaotic emission. This building block represents a key tool to implement a high degree of privacy directly on the physical layer. The team has built a proof-of-concept communication at a wavelength of 5.7 μm with a message encryption at a bit rate of 0.5 Mbit/s. Their demonstration of private free-space communication between […]
Using micro-sized cut metal wires, team forges path to new uses for terahertz waves
Phys.org May 14, 2021 Terahertz flat optics is a design concept for replacing conventional three-dimensional bulky optical components with two-dimensional ultra-thin optical components. However, high refractive index materials suitable for flat optics are frequently subject to high Fresnel reflections due to the cumbersome control of the relative permeability it requires. Researchers in Japan fabricated metasurface consisting of 80,036 pairs of cut metal wires on both the front and back of a 5 μm-thick polyimide film with a super-fine ink-jet printer using silver paste ink. They have experimentally shown that the metasurface is reflectionless, has a high refractive index, extremely low […]
Researchers realize coherent storage of light over one hour
Phys.org May 10, 2021 One solution for remote quantum communication lies in quantum memories: photons are stored in long-lived quantum memory (quantum flash drive) and then quantum information is transmitted by the transportation of the quantum memory. Researchers in China adopted the spin wave atomic frequency comb (AFC) protocol in a ZEFOZ field (ZEFOZ-AFC) method to implement long-lived storage of light signals. They used dynamical decoupling to protect spin coherence and extend storage time. They demonstrated coherent storage of light in an atomic frequency comb memory over 1 hour with a fidelity of 96.4%. The study meets the basic requirements […]
Flexible, easy-to-scale nanoribbons move graphene toward use in tech applications
Science Daily May 3, 2021 Silicon-based fiber optics are currently the best structures for high-speed, long distance transmissions, but graphene could improve performance even more. Researchers at the University of Wisconsin created a scalable fabrication technique to make the smallest graphene ribbon structures. They found that to improve graphene’s performance is to cut it into microscopic, nanometer-scale ribbon structures, which act as tiny antennas that interact with light. The smaller the antenna, the higher energies of light it interacts with. As the ribbon width decreases, so does the resonant wavelength of light. Lower wavelengths mean higher energies, and their devices interacted […]
Researchers complete high-precision time-frequency dissemination
Phys.org April 26, 2021 Microwave-based satellite–ground links cannot fully satisfy the requirements of metrology, navigation, positioning, and very long baseline interferometers. Researchers in China investigated the possibility of an optical-based satellite–ground link, where the transferred carriers are pulsed lasers, resulting in a link with a high time resolution and a large ambiguous range. They analyzed the parameters of satellites in different orbits and concluded that high-orbit links enable more stable time–frequency comparison or dissemination by taking advantage of the long duration, a large common view range, and the lower relativistic effects. They performed a 16 km free-space transfer experiment to […]
Counting single photons at unprecedented rates
Phys.org April 13, 2021 Researchers at NIST have demonstrated a method that allows a high-efficiency single-photon-avalanche diode (SPAD) with a thick absorption region to count single photons at rates significantly higher than previously demonstrated. They applied large (>30 V) AC bias gates to the SPAD at 1 GHz and detected minute avalanches by means of radio frequency interferometry. They measured a reduction by a factor of ≈500 in the average charge per avalanche when compared to operation in its traditional active-quenching module and a relative increase in >19% in detection efficiency at 850 nm. The reduction in charge strongly suppresses self-heating effects in the […]