Science Daily May 7, 2019 Researchers in Japan have developed a method for identifying the location of point-like scatterers based on fluctuations in the physical properties of the surface. They extracted information on the far-field wave properties of the Green’s function by using the so-called “steepest descent path” and “pseudo-projections” methods. Then, the far-field operator was defined based on the near-field observation and the far-field properties of the Green’s function. They used this far-field operator to obtain the indicator functions that determine the position of the scatterers. They successfully demonstrated the reconstruction of densely packed point-like scatterers using the sensor […]
Tag Archives: S&T Japan
Study opens a new route to achieving invisibility without using metamaterials
Phys.org April 23, 2019 Researchers in Japan report a way of making a cylinder invisible without a cloak for monochromatic illumination at optical frequency including those visible to the human eye. Based on Mie scattering they looked for a region indicating very low scattering efficiency, which they knew would correspond to the cylinder’s invisibility and determined that in this region invisibility would occur when the refractive index of the cylinder ranges from 2.7 to 3.8. Natural materials such as silicon, aluminum arsenide and germanium arsenide, which are commonly used in semiconductor technology fall in this category. They found that the […]
Ultrafast Cluster Electronics
Next Bi Future April 12, 2019 Researchers in Japan combined quantum chemical and molecular dynamic calculations to predict how clusters of molecules behave and interact over time providing critical insight for future electronics. They used their method to predict the changes in a computer-simulated cluster of benzene molecules over time. When light is applied to the T-shaped benzene clusters, they reorganize themselves into a single stack; an interaction known as pi-stacking. This modification from one shape to another changes the cluster’s electrical conductivity, making it act like an on-off switch. They simulated the addition of a molecule of water to […]
High-capacity transmission over multi-core fiber link with 19-core optical amplifier
Eurekalert April 8, 2019 The successful development of Space-Division-Multiplexing (SDM) amplifiers is crucial for commercial realization of SDM technologies. Researchers in Japan developed a 19-core Erbium-doped-fiber amplifier utilizing cladding-pumping technology in order to share electrical power between the large number of spatial channels. The amplifier was integrated into a transmission test bed of for a record transmission demonstration. Fully decoded optical data transmission of 715 Tb/s was achieved over 2,009 km using coded polarization division multiplexed (PDM) -16 quadrature-amplitude modulation (QAM) of 345 carriers over the C and L band in a re-circulating transmission loop. The research enables development of […]
Copper-based alternative for next-generation electronics
Science Daily April 1, 2019 In the existing techniques for the preparation of copper nanoparticles, impurities can be removed via extremely high temperatures hence those prepared at room temperature could not solidify into usable parts. Researchers in Japan have synthesised copper nanoparticles with the ability to solidify at much lower temperatures, remain pure; they altered the structure of the copper nanoparticles and rendered them more stable so that they do not degrade at low temperatures. With the new technique copper nanoparticle-based materials can be utilized in various types of on-demand flexible and wearable devices which can be fabricated easily via […]
Ferromagnetic nanoparticle systems show promise for ultrahigh-speed spintronics
Phys.org March 28, 2019 Based on their previous discovery that the “electric field” component of a terahertz pulse plays a key role in the terahertz magnetization modulation of semiconductor-based ferromagnetic materials, researchers in Japan embedded MnAs ferromagnetic nanoparticles in a GaAs host matrix. They observed a large modulation up to 20% of the magnetization of the nanoparticles with terahertz pump pulse irradiation. They found that the modulation is induced by the electric-field component of the terahertz pulse via spin-carrier interactions. The results will lead to an ultrafast coherent magnetization reversal within a picosecond, which will be an essential technique for […]
Unlocking the untapped potential of light in optical communications
Phys.org March 8, 2019 The optical vortex carries the orbital angular momentum of light and can be used to multiplex signals by assigning each signal to a light wave of different momentum. Researchers in Japan designed and fabricated an orbital angular momentum multiplexing/demultiplexing module that could take five independent signals as input. Using a combination of two tiny circuit structures, called a star coupler and an optical-vortex generator, each of the five signals is “encoded” with a unique optical angular momentum. The output signal consists of a combination of the five signals, and the receiver circuit carries out the multiplexing […]
Organic electronics: Scientists develop a high-performance unipolar n-type thin-film transistor
Science Daily March 1, 2019 Researchers in Japan used a series of new poly(benzothiadiazole-naphthalenediimide) derivatives and fine-tuned the material’s backbone conformation introducing vinylene bridges capable of forming hydrogen bonds with neighboring fluorine and oxygen atoms. Overall, the resultant material had an improved molecular packaging order and greater strength, which contributed to the increased electron mobility. The material achieved an electron mobility of 7.16 cm2 V-1 s-1, representing more than a 40 percent increase over previous comparable results.The researchers will also aim to improve the air stability of n-channel transistors — a crucial issue for realizing practical applications that would include […]
Magnetization reversal achieved at room temperature using only an electric field
Science Daily February 2, 2019 Researchers in Japan report direct observation of out-of-plane magnetization reversal at room temperature by magnetic force microscopy after electric polarization switching of cobalt-substituted bismuth ferrite thin film grown on GdScO3 substrate. A striped pattern of ferroelectric and weakly ferromagnetic domains was preserved after reversal of the out-of-plane electric polarization. The discovery of magnetic reversal using an electric field paves the way to low power-consumption, non-volatile magnetic memories, such as magnetoresistive random-access memories…read more. TECHNICAL ARTICLE
Toward Ghost Imaging on a Chip
Optics and Photonics February 12, 2019 To overcome the bulky spatial light modulators and other optical components for ghost imaging, researchers in Japan used a phased array of 128 tiny phase shifters packed onto a chip with a 4×4-mm footprint. In the chip setup, input light from a 1550-nm laser, coupled into the array via a lensed fiber, is split into 128 waveguides and piped into the phase-shifting elements of the array. Each individual phase shifter can be electrically controlled, allowing rapid creation of a series of random speckled patterns at refresh rates faster than the few-frame-per-second. The random pattern […]