Phys.org October 11, 2023 Orbital angular momentum (OAM) generators based on metasurfaces can achieve ultracompact designs. However, they generally have limited working bandwidth and require complex designs and multistep time-consuming fabrication processes. Researchers in Australia designed broadband graphene OAM metalenses with flexibly controlled topological charges using the detour phase method and fabricated using ultrafast laser nanoprinting. The experimental results agreed well with the theoretical predictions, which demonstrated the accuracy of the design method. The broadband graphene OAM metalenses have broad applications in miniaturized and integrated photonic devices enabled by OAM beams… read more. Open Access TECHNICAL ARTICLE
Tag Archives: optical communication
Protecting light communication with random objects
Phys.org July 17, 2023 Researchers in the Netherlands have developed an optical communication system with two scattering layers to hide both the sender and receiver, by measuring the correlation of the intermediate speckle generated between the two layers. The binary message is modulated as spatially shaped wavefronts, and the high number of transmission modes of the scattering layers allowed for many uncorrelated incident wavefronts to send the same message, making it difficult for an attacker to intercept or decode the message and thus increasing secrecy. They collected 50,000 intermediate speckle patterns and analyzed their correlation distribution using the Kolmogorov-Smirnov (K-S) […]
Generation of color-tunable high-performance LG laser beams via Janus OPO
Phys.org April 24, 2023 Laguerre-Gaussian (LG) modes of light wave can carry the external torque of photons as they move through space. However, LG mode laser sources do not yet exist. An international team of researchers (China, USA – University of Arkansas) has experimentally demonstrated highly efficient, highly pure, broadly tunable, and topological-charge-controllable LG modes from a Janus optical parametric oscillator (OPO). They designed the Janus OPO featuring a two-faced cavity mode to guarantee an efficient evolution from a Gaussian-shaped fundamental pump mode to a desired LG parametric mode. The output LG mode had a tunable wavelength between 1.5 and […]
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 shield blocks electromagnetic interference while allowing wireless optical signals
Phys.org January 25,2023 An international team of researchers (Sweden, China) experimentally demonstrated, for the first time, a mechanically flexible silver mesh that is visibly transparent, allows high-quality infrared wireless optical communication and efficiently shields electromagnetic interference in the X band portion of the microwave radio region. The Ag mesh/polyethylene (PE) achieved high average EMI shielding effectiveness (SE) of 28.8 dB in the X band with an overall transmittance of 80.9% at 550 nm. With a polydimethylsiloxane (PDMS) coating, the average EMI SE was still up to 26.2 dB and the overall transmittance was increased to 84.5% at 550 nm due […]
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 […]
Researchers demonstrate 40-channel optical communication link, capable of transmitting 400 GB of data per second
Phys.org June 9, 2022 A team of researchers in the US (University of Central Florida, NIST, Stanford University, University of Pennsylvania) has experimentally demonstrated a 400 Gbit/s optical communication link utilizing wavelength-division multiplexing and mode-division multiplexing for a total of 40 channels. This link utilizes a 400 GHz frequency comb source based on a chip-scale photonic crystal resonator. Silicon-on-insulator photonic inverse-designed 4 × 4 mode-division multiplexer structures enabled a fourfold increase in data capacity. They showed less than −10 dBm of optical receiver power for error-free data transmission in 34 out of a total of 40 channels using a PRBS31 pattern…read more. TECHNICAL ARTICLE
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 […]
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 […]
A performance leap for graphene modulators in next generation datacom and telecom
Nanowerk February 16, 2021 Electro-absorption (EA) waveguide-coupled modulators are essential building blocks for on-chip optical communications. Compared to state-of-the-art silicon devices, graphene-based EA modulators promise smaller footprints, larger temperature stability, cost-effective integration, and high speeds. However, combining high speed and large modulation efficiencies in a single graphene-based device has remained elusive so far. An international team of researchers (Spain, Italy, Belgium) overcame this fundamental trade-off by demonstrating the 2D-3D dielectric integration in a high-quality encapsulated graphene device. They integrated hafnium oxide and two-dimensional hexagonal boron nitride within the insulating section of a double-layer graphene EA modulator. This combination of materials […]