Phys.org December 10, 2024 An international team of researchers (Israel, USA – UT Austin, Los Alamos National Laboratory, Germany, Italy) harnessed the potential of radially polarized photons for classical and quantum communication applications to demonstrate an on-chip, room-temperature device, which generated highly directional radially polarized photons at very high rates. The photons were emitted from a giant CdSe/CdS colloidal quantum dot (gQD) accurately positioned at the tip of a metal nanocone centered inside a hybrid metal-dielectric bullseye antenna. They showed that the emitted photons could have a very high degree of radial polarization, based on a quantitative metric. According to […]
Category Archives: Communications technology
Optical amplifier and record-sensitive receiver pave the way for faster space communication
Phys.org October 30, 2024 Conventional optical amplifiers that use stimulated emission suffer from the generation of excess noise, thus limiting the performance in many applications. The phase-sensitive optical parametric amplifier can approach a noise figure of 0 dB. However, its implementation in optical communication links is cumbersome due to increased complexity. An international team of researchers (Sweden, Sri Lanka) proposed and demonstrated an implementation of a transmission system using a standalone ultralow-noise phase-sensitively preamplified receiver and a conventional single-wave optical transmitter. According to the researchers their approach was simple and could transform amplifiers to practical use, such as deep-space-to-earth communication […]
All-optical switch device paves way for faster fiber-optic communication
Phys.org October 19, 2024 Optical Stark effect is an example of using Floquet engineering for optical trapping of atoms and breaking time-reversal symmetry in solids. However, floquet engineering typically requires high field intensities obtained in ultrafast pulses, severely limiting its use. An international team of researchers (USA – University of Michigan, Japan, Taiwan) demonstrated using cavity engineering of the vacuum modes to achieve Floquet effects at an extremely low fluence of 450 photons/μm2. At higher fluences, the cavity-enhanced Floquet effects led to 50 meV spin and valley splitting of WSe2 excitons, corresponding to an enormous time-reversal breaking. They demonstrated an […]
Harnessing quantum principles: Phased arrays within phased arrays for smarter, greener indoor optical wireless networks
Phys.org October 11, 2024 Researchers in Australia developed a novel approach for enhancing signal radiation patterns in optical wireless networks utilizing a planar optical aperture incorporated with infrared radiative element clusters to optimize signal radiation patterns through selective cluster excitation. They used dual carrier wavelength approach, leveraging an effectively large carrier wavelength for the system to avoid grating lobes occurrence due to distributed clusters. They used optimization-based algorithm to ensure optimized signal reception at the specific receiver location. Using simulations, they demonstrated the behavior of parameters like side lobe level, focal spot area, and power efficiency within the focal spot […]
Novel visible light communication encryption technology uses chiral nanoparticles
Phys.org October 10,2024 Although recent advancements have been made in active emission or passive conversion of polarized light through solution-processed nanomaterials or metasurfaces, the design paths usually encounter limitations. To address these challenges researchers in the Republic of Korea integrated the spatiotemporal modulation of the LED device, the precise control and efficient polarization emission, and the programmable patterning/positioning using 3D printing. They showed high degree of polarization for both linearly and circularly polarized emission from ultrathin inorganic nanowires and quantum nanorods due to the shear-force-induced alignment effect during the protruding of printing filaments. Real-time polarization modulation was obtained through the […]
Advanced orbital angular momentum mode switching in multimode fiber utilizing an optical neural network chip
Phys.org August 21, 2024 Existing optical switching solutions are inadequate for addressing flexible information exchange among the mode channels. Researchers in China introduced a flexible mode switching system in a multimode fibre based on an optical neural network chip. The system utilized the flexibility of on-chip optical neural networks along with an all-fibre orbital angular momentum (OAM) mode multiplexer-demultiplexer to achieve mode switching among the three OAM modes within a multimode fibre. They validated the system by successfully transmitting different modulation formats across various modes. According to the researchers their system could provide effective optical switching in practical multimode communication […]
Researchers develop technology to mass produce quantum dot lasers for optical communications
Phys.org June 28, 2024 To produce 75 °C continuous-wave operation research in South Korea investigated InAs/GaAs quantum dot laser diodes (QDLDs) on a GaAs substrate grown by utilizing all-metalorganic chemical vapor deposition technology with a p-AlGaAs cladding layer. The InAs quantum dots (QDs) in a dot-in-a-well (DWELL) structure formed by engineering the strained bottom InGaAs layer were successfully grown without detectable clusters, making it possible to increase the number of DWELL stacks effectively. The results of electron-channeling contrast imaging revealed that dislocations in the p-cladding layer were generated due to the accumulative strain of the DWELL and low-temperature growth. The […]
Scientists achieve first intercity quantum key distribution with deterministic single-photon source
Phys.org July 3, 2024 Quantum key distribution (QKD) enables secure communication. Semiconductor quantum dots (QDs) are a promising building block for quantum communication applications because of the deterministic emission of single photons with high brightness and low multiphoton contribution. Researchers in Germany reported on the first intercity QKD experiment using a bright deterministic single photon source. A BB84 [one time pad encryption] protocol based on polarisation encoding was realized using the high-rate single photons in the telecommunication C-band emitted from a semiconductor QD embedded in a circular Bragg grating structure. Utilizing the 79 km long link (equivalent to 130 km for the […]
Scientists crack new method for high-capacity, secure quantum communication
Phys.org July 2, 2024 To achieve global quantum internet preparing and manipulating N-dimensional flying qudits as well as subsequently establishing their entanglement are still challenging tasks. A team of researchers in the US (University of Pennsylvania, Duke University, College of Staten Island) used an integrated approach, to explore the synergy from two degrees of freedom of light, spatial mode and polarization, to generate, encode, and manipulate flying structured photons and their formed qudits in a four-dimensional Hilbert space with high quantum fidelity, intrinsically enabling enhanced noise resilience and higher quantum data rates. The four eigen spin–orbit modes of their qudits […]
Making ferromagnets ready for ultra-fast communication and computation technology
Phys.org June 14, 2024 Spin-torque driven critical spin dynamics, such as auto-oscillations, play the central role in many spin-based technologies. An international team of researchers (USA – UC Riverside, Johns Hopkins University, Germany, India, Ukraine) developed the theoretical framework of precessional auto-oscillations for ferromagnets with spin inertia. They discovered and introduced the concept of nutational auto-oscillations and demonstrated that they can become pivotal for future ultrahigh frequency technologies. They showed parallels between spin dynamics in ferrimagnets and inertial ferromagnets and derived an isomorphism that established a foundation for synergistic knowledge transfer between these research fields… read more. TECHNICAL ARTICLE