Phys.org October 24, 2022 After experimentally studying the optical properties of dielectric reflective metalenses including their off-axis focusing performance, researchers in Saudi Arabia proposed reflective metalens based on titanium dioxide (TiO2) and silicon dioxide (SiO2), which operate at a visible wavelength of 0.633 µm. Unlike conventional reflective metalenses based on metallic mirrors, the proposed device was designed based on a modified parabolic phase profile and was integrated onto a dielectric distributed Bragg reflector periodic structure to achieve high reflectivity with five dielectric pairs. The focusing efficiency characteristics of the metalens were experimentally studied for beam angles of incidence between 0∘ […]
Tag Archives: S&T Saudi Arabia
Explaining electric fields in sandstorms
Phys.org April 27, 2021 Sandstorms can generate high-magnitude electrical fields capable of disrupting communication equipment. Recent studies have shown that sand can pick up static electricity through collisions that take place near the ground. To resolve the motion of sand particles researchers in Saudi Arabia created a large-eddy simulation, where the tiny fluctuations get smoothed over and only large ones remain. They modeled the turbulent eddies of sandstorms inside a virtual box that stretches from ground level to kilometer-scale heights in the atmosphere. The sandstorm’s strength was controlled with an algorithm that introduced different densities of charged particles into the […]
Innovative flat optics will usher the next technological revolution
EurekAlert March 8, 2021 Critical challenges for real-world applications of flat optics technology are due to the limited operational efficiency in the visible region, on average lower than 60%, which originates from absorption losses in wavelength-thick structures and the realization of on-demand optical components for controlling vectorial light at visible frequencies simultaneously in both reflection and transmission and with a predetermined wavefront shape. Researcher in Saudi Arabia have developed an inverse design approach that allows the realization of highly efficient (up to 99%) ultrathin (down to 50 nm thick) optics for vectorial light control with broadband input–output responses in the visible […]
Researchers Use Lasers to Bring the Internet Under the Sea
IEEE Spectrum June 22, 2020 Researchers in Saudi Arabia have developed underwater WiFi which they call Aqua-Fi. The system is fully compliant with IEEE 802.11 wireless standards. A Wi-Fi signal was used to connect the device to a Raspberry Pi functioning as a modem. The modem converted the wireless signal to an optical signal (in this case, a laser) that was beamed to the receiver attached to a surface buoy. From there, established communications techniques were used to send the signal to an orbiting satellite. For the underwater device to receive data, the process is simply reversed. The system is […]
Robots learn by checking in on team members
Phys.org June 13, 2018 Researchers in Saudi Arabia have developed the software and hardware needed to coordinate a team of UAVs that can communicate and work toward a common goal. They custom-built UAVs and incorporated a lightweight, low-power computing and wi-fi module on each one so that they could talk to each other during flight. Each drone makes its own plan based on a forecast of optimistic views of their teammates’ actions and pessimistic views of the opponent’s actions. They used Capture the Flag game scenario to test the drones. Their algorithm worked well in both indoor and outdoor arenas […]
Tuning in to magnetic ink
Eurekalert April 4, 2018 By injecting iron-based reagents into a hot acetic acid solution, researchers in Saudi Arabia synthesized magnetic iron-oxide nanoparticles that dispersed into deionized water to form an ink. When deposited as a thin film on a glass substrate, the new magnetic substrate could act as an energy-storing inductor device with an adjustable capacity of over 20 percent. By modifying the nanoparticles’ surfaces with hydrocarbon chains, they were able to produce free-standing magnetic sheets of a few millimeters in thickness. The discovery boosts prospects for inexpensive electronics that work worldwide by tuning in to multiple cellular bands and […]
Innovative diode design uses ultrafast quantum tunneling to harvest infrared energy from the environment
Phys org February 5, 2018 Researchers in Saudi Arabia have designed a device, rectenna, that can tap into the infrared radiation in the environment and waste heat from industrial processes and transform quadrillionth-of-a-second wave signals into useful electricity. Tunneling devices, such as metal-insulator-metal (MIM) diodes, rectify infrared waves into current by moving electrons through a small barrier. They used a ‘bowtie-shaped’ nano-antenna that sandwiches the thin insulator film between two slightly overlapped metallic arms to generate the intense fields needed for tunneling… read more.