EurekAlert November 18, 2019 Numerous examples of photonic band gaps have been shown previously in various types of crystals. With computational simulations researchers at Princeton University have shown that a Weaire-Phelan foam would allow some frequencies of light to pass through while completely reflecting others making it a photonic band gap material. The photonic band gap has a maximal size of 16.9% (at a volume fraction of 21.6% for a dielectric contrast ε=13) and a high degree of isotropy. With further development, the foam could transport and manipulate light used in telecommunications. Photonic band gap materials could guide the light […]
This humidity digester breathes in atmospheric water and exhales energy
Science Daily November 20, 2019 Researchers in Singapore have developed a humidity digester composed of a moisture hydrogel based zinc and cobalt, cathode, photoanode, and a solar cell. Just like batteries, it generates power from atmospheric humidity instead of an electrolyte. The photoanodes, acting as a photo-electrocatalyst, oxidize the absorbed water in the presence of light to split water and produce energy. The hydrogel constantly replenishes the system with water that is pulled out from the air to sustain the energy generation process. The assembly generates electricity while dehumidifying the room. The second-generation cobalt hydrogel absorbs moisture faster than any […]
Kick-starting Moore’s Law? New ‘synthetic’ method for making microchips could help
Phys.org November 18, 2019 By using specially treated silicon surfaces to tailor the crystals’ size and shape, an international team of researchers (USA – Johns Hopkins University, University of Pennsylvania, Naval Research Laboratory, South Korea) has found a potentially faster and less expensive way to produce next-generation semiconductor crystals for microchips. They doused silicon substrates with phosphine gas and grew crystals on it. They discovered that the reaction of phosphine with the silicon support caused the crystals to grow as horizontal “ribbons” as opposed to the planar and triangularly shaped sheets. The research could enable new scientific discoveries and accelerate […]
Making tiny antennas for wearable electronics
Science Daily November 20, 2019 Researchers in South Korea made the antenna by spray-coating several layers of NbSe2 nanosheets onto a plastic substrate. In tests an 885 nm-thick antenna, a 10 × 10 mm patch of the ultrathin material performed well, with a radiation efficiency of 70.6% propagating radio frequency waves in all directions. By changing the length of the antenna, the frequency could be tuned from 2.01 to 2.80 GHz, which includes the frequency required by Bluetooth and Wi-Fi technologies. The antenna could be bent and stretched without large changes in its performance. In addition to wearable electronics, the […]
Nanooptical traps: A promising building block for quantum technologies
Phys.org November 19, 2019 By controlling individual atoms, quantum properties can be investigated and made usable for technological applications. However, the applicability of this technology has been limited because the atoms become very hot after a very short time and are lost. An international team of researchers (Austria, Germany) has carefully analyzed the system. With their theoretical model, they were able to show that a certain form of mechanical vibration of the glass fiber is responsible for the strong heating of the particles. This finding has important consequences for applications. The technology can be significantly improved with simple countermeasures, longer […]
New water-based optical device revolutionizes the field of optics research
Phys.org November 20, 2019 Researchers in Japan have developed a light modulator using the Pockels effect of water in a nanometer-thick electric double layer on an electrode surface. The modulator comprises a transparent-oxide electrode on a glass substrate immersed in an aqueous electrolyte solution. When an optical beam is incident such that it is totally reflected at the electrode-water interface, the light is modulated at a specific wavelength with a near-100% modulation depth synchronized with the frequency of the applied AC voltage. Pockels effect has applications in optical engineering, optical communication, displays and electric sensors and the enhancement principle opens […]
Researchers create better light-trapping devices
Phys.org November 18, 2019 Optical resonators’ performance is often limited by out-of-plane-scattering losses caused by inevitable fabrication imperfections. An international team of researchers (China, USA – MIT, University of Pennsylvania) proposed and experimentally demonstrated a class of guided resonances in photonic crystal slabs, in which out-of-plane-scattering losses are strongly suppressed by their topological nature. These resonances arise when multiple bound states in the continuum, merge in momentum space and enhance the quality factors Q of all nearby resonances in the same band. Using such resonances in the telecommunication regime, they experimentally achieved quality factor 10 times greater than other devices […]
A review of single molecule-based electronic devices
Eurekalert November 21, 2019 At present traditional electronic devices based on semiconductor materials are facing technical, technological limitations and theoretical limitations. Single molecule electronic devices are considered one of the most hopeful candidates. Researchers in China provide an overview of single molecule electronic devices, including molecular electronic devices and electrode types. Several molecular electronic devices are presented, including molecular diodes, molecular memories, molecular wires, molecular field effect transistors (FET) and molecular switches. The influence of different electrode types of the transport characteristics and other characteristics of molecular devices are briefly introduced, such as potential thermoelectric effects. The future challenges to […]
Synthetic biologists developing a new class of high-performance materials
Science Daily November 18, 2019 A team of researchers in the US (Northwestern University, University of Illinois, Stanford University, UT Austin, industry) developed a set of design rules to guide how ribosomes, a cell structure that makes protein, can incorporate new kinds of monomers, which can be bonded with identical molecules to form polymers. The rules guide how ribosomes, a cell structure that makes protein, can incorporate new kinds of monomers, which can be bonded with identical molecules to form polymers. These findings are an exciting step forward to achieving sequence-defined synthetic polymers. The ability to harness and adapt cellular […]
A technique to measure mechanical motion beyond the quantum limit
Phys.org November 20, 2019 Through the interaction of the mechanical oscillator with a microwave (or optical) cavity, back-action evading measurement in principle enables noiseless measurement of the position of the mechanical oscillator. However, additional interactions between the microwave (or optical) field and the mechanical oscillator lead to instabilities in mechanical motion, which prevents continuous measurement. Through simultaneous but unequal electromechanical amplification and cooling processes, a team of researchers in the US (industry, University of Colorado, NIST) created a method for a nearly noiseless pulsed measurement of mechanical motion. The conversion of signals between these two disparate frequency bands is important […]