Science Daily February 15, 2022 Terahertz waveguides are required to provide versatile signal-processing functionalities. Despite fundamental components they typically rely on complex hybridization, in turn making it extremely challenging to go beyond the most elementary functions. An international team of researchers (Canada, Italy, Germany) has proposed a universal approach, in which multiscale-structured Bragg gratings can be directly etched on metal-wires. They designed a four-wire waveguide geometry, amenable to support the low-loss and low-dispersion propagation of polarization-division multiplexed terahertz signals. By engraving on the wires judiciously designed Bragg gratings based on multiscale structures, they demonstrated that it is possible to independently […]
Category Archives: Communications technology
Researchers use solar cells to achieve fast underwater wireless communication
Science Daily February 16, 2022 The greatest problem in using solar panels for underwater wireless optical communication (UWOC) systems is the limited bandwidth of the solar panel, which was originally optimized for energy harvesting rather than communication. Researchers in China studied the fundamentals of the solar array and proposed series-connected solar arrays for high-speed underwater detection. As they increased the size of the solar array from 1×1 to 3×3, the −20-dB bandwidth increased from 4.7 MHz to 24.2 MHz. To further improve the frequency response, they applied a reverse bias on the array. With a reverse bias voltage of 90 […]
New chip hides wireless messages in plain sight
Science Daily November 23, 2021 Traditional encryption methods are challenging to scale for high-bandwidth, ultralow-latency applications. An alternative approach is to use physical-layer techniques that rely on the physics of signal propagation to incorporate security features without the need for an explicit key exchange. Ensuring security using directional, narrow-beam-like features of mm-wave/THz signals has proven to be vulnerable to passive eavesdroppers. An international team of researchers (USA – Princeton University, China) has developed a space-time modulation approach that ensures security by enforcing loss of information through selective spectral aliasing towards the direction of eavesdroppers, even though the channel can be […]
Nuclear radiation used to transmit digital data wireless
Phys.org November 10, 2021 An international team of researchers (UK, Slovenia) reports on the configuration and operation of a nuclear instrumentation set-up designed to transmit digitally encoded information using fast neutrons. They measured the spontaneous emission of fast neutrons from californium-252, a radioactive isotope produced in nuclear reactors. Modulated emissions were measured using a detector and recorded. A word, the alphabet and a random number selected blindly, were encoded serially into the modulation of the neutron field and the output decoded on a laptop which recovered the encoded information on screen. A double-blind test was performed in which a number […]
Controlling light with a material three atoms thick
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 […]
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 […]