Nanowerk March 16, 2023 Researchers in Hong Kong has invented a synthetic phase design of rotary doublet Airy beam and triplet Gaussian beam varifocal meta-devices to fully control the terahertz beam’s propagation direction and coverage area. The focusing spot can be delivered to arbitrary positions in a two-dimensional plane or a three-dimensional space. The highly concentrated signal can be delivered to a specific position, and the transmission direction can be adjusted freely to enable secure, flexible, and high-directivity 6G communication systems. According to the researchers this technology avoids the high costs associated with extensive use of active components. 6G communication […]
Category Archives: Communications technology
New method enables effective free-space optical communication regardless of weather
Phys.org March 1, 2023 To overcome the barriers to light propagation for free-space optical communication (FSO) a team of researchers in the US (Rensselaer Polytechnic Institute, University of Michigan) proposed making use of the acoustic properties of a laser filament coupled together with a donut-shaped signal beam. A filament generated by an ultrafast laser was accompanied by an acoustic wave that clears a cylindrical chamber around the filament’s plasma column that can mimic a transmission channel. They presented a method to couple a Laguerre–Gauss beam through the obstacle-free channel. They imaged and measured the transmitted signal carried by the structured […]
New photodiode with extremely low excess noise for optical communication and long-range LIDAR
Phys.org February 9, 2023 Avalanche photodiodes (APDs) have internal gain, which means that when compared to PIN-photodiodes they typically have a higher signal-to-noise ratio. Researchers in the UK designed and demonstrated photodiode that exhibits high multiplication factor with very little added noise. The new semiconductor alloy is based on a GaAsSb absorption region that has excellent detection efficiency at infrared wavelengths (up to 1,700 nanometers). The device incorporated an appropriate doping profile to suppress tunneling current from the absorption region, achieving a large avalanche gain, ∼130 at room temperature. It exhibits extremely low excess noise factors of 1.52 and 2.48 […]
Signal processing algorithms improved turbulence in free-space optic tests
Science Daily December 20, 2022 Researchers in the UK used commercially available photonic lanterns, a commercial transponder, and a spatial light modulator to emulate turbulence. They simultaneously transmitted multiple data signals using different spatially shaped beams of light using a photonic lantern. By detecting light with these shapes using a second lantern, more of the light is collected at the receiver, and the original data can be unscrambled greatly reduce the impact of the atmosphere on the quality of the data received in MIMO digital signal processing. By transmitting multiple beams of different shapes through the same telescopes and detecting […]
New communications technology: Super-fast optical lasers
Science Daily November 9, 2022 While enabling orders-of-magnitude gains in data rates, optical signals impose much stricter pointing requirements and are strongly affected by atmospheric turbulence. Researchers in Australia established a coherent 1550 nm link across turbulent atmosphere between a deployable optical terminal and a drone-mounted retroreflector. Through 10 Hz machine vision optical tracking with nested 200 Hz tip/tilt adaptive optics stabilisation, they corrected for pointing errors and atmospheric turbulence to maintain robust single mode fiber coupling, resulting in an uninterrupted 100 Gbps optical data link while tracking at angular rates of up to 1.5 deg/s, equivalent to that of […]
Erbium atoms in silicon: A prime candidate for quantum networks
Phys.org November 7, 2022 A major challenge for a scalable architecture for quantum information processing is based on emitters in nanostructures that are coupled by light. Researchers in Germany demonstrated the integration of erbium atoms with special optical properties into a silicon crystal. Thus, the atoms could be connected by light at a wavelength that is commonly used in telecommunications, making them ideal building blocks for future quantum networks that enable calculations with several quantum computers, as well as the secure exchange of data in a quantum internet. They achieved a narrow inhomogeneous broadening, less than 1 GHz, strong optical […]
Unipolar quantum optoelectronic devices: Higher speeds in free-space optical communications in the midinfrared band
Phys.org November 2, 2022 A recently demonstrated proof-of-concept of high-speed transmission taking advantage of intersubband devices was limited by the short-distance optical path (up to 1 m). An international team of researchers (France, USA -University of Central Florida, University of New Mexico) used an uncooled quantum cascade detector and a nitrogen-cooled quantum well-infrared photodetector to study the possibility of building a long-range link using unipolar quantum optoelectronics. They evaluated the maximum data rate of their link in a back-to-back configuration before adding a Herriott cell to increase the length of the light path up to 31m. By using pulse shaping, […]
A Single Laser Transmitted a Second’s Worth of Internet Traffic in Record Time
Science Alert October 25, 2022 As essential core technologies for optical fibre communication are approaching their limits of size, speed and energy-efficiency, there is a need for new technologies that offer further scaling of data transmission capacity. An international team of researchers (Denmark, Sweden, Japan) has shown that a single optical frequency-comb source based on a silicon nitride ring resonator supports data capacities in the petabit-per-second regime. They experimentally demonstrated transmission of 1.84 Pbit s–1 over a 37-core, 7.9-km-long fibre using 223 wavelength channels derived from a single microcomb ring resonator producing a stabilized dark-pulse Kerr frequency comb. They presented a theoretical […]
Antenna enables advanced satellite communications testing
MIT News September 6, 2022 Researchers at MIT Lincoln Laboratory have installed a Multi-Band Test Terminal (MBTT) which can rotate 15 degrees per second, completing a single revolution in 24 seconds. At this speed, the MBTT can detect and track satellites in medium and low Earth orbit. The MBTT is designed to be easily reconfigured to support multiple radio frequency (RF) bands used for military and commercial satellite SATCOM systems. Since its installation, it has supported a wide range of tests and experiments involving protected tactical waveform (PTW). It is also supporting international outreach efforts led by Space Systems Command […]
DARPA Kicks Off Program to Develop Low-Earth Orbit Satellite ‘Translator’
DARPA August 10, 2022 DARPA has selected 11 teams, from academia and large and small commercial companies, for Phase 1 of the Space-Based Adaptive Communications Node program, known as Space-BACN. Space-BACN aims to create a low-cost, reconfigurable optical communications terminal that adapts to most optical intersatellite link standards, translating between diverse satellite constellations. It would create an “internet” of low-Earth orbit (LEO) satellites, enabling seamless communication between military/government and commercial/civil satellite constellations that currently are unable to talk with each other. Phase 1 of Space- BACN spans 14 months and will conclude with a preliminary design review for the first […]