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 […]
Tag Archives: S&T Japan
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 […]
Sodium is the new lithium: Researchers find a way to boost sodium-ion battery performance
Science Daily February 1, 2019 Sodium ion batteries meet the demand for large-scale energy storage. By investing ~4300 candidates via a high-throughput computation, researchers in Japan have identified nanotube-type Na2V3O7 as a cathode material because of its fast sodium diffusivity. High-rate performance was confirmed, showing ~65% capacity retention at a current density of 10C at room temperature, despite the large particle size of >5 μm. But they found that Na2V3O7 underwent deterioration in the final charging stages, which limits the practical storage capacity to the half of theoretical one. In their future experiments, the researchers aim to focus on improving the […]
Computational algorithm to reduce electromagnetic noise in electronic circuits developed
Science Daily January 31, 2019 Researchers in Japan developed algorithm for computer simulation of electric circuits in which transmission lines are connected with lumped element models. They introduced the incidence matrix found in circuit theory and time domain impedance to connect partial differential equations and ordinary differential equations which are used to solve transmission line problems. Based on the results of calculations using this algorithm, the researchers demonstrated that EM noise could be reduced by using the symmetric 3-line configuration of the circuit. Their calculation method is for one-dimensional multi-conductor transmission lines, but they have already developed a calculation algorithm […]
Materials that open in the heat of the moment
Science Daily January 24, 2019 The porous nanomaterials that are currently used for gas separation and storage are not tunable: their pores are persistent and rigid. Researchers in Japan designed a porous coordination polymer with copper atoms linked by butterfly-shaped ligands made from isophthalic acid and phenothiazine-5,5-dioxide. The material was comprised of tiny nanocages with protruding channels. At very low temperatures, the channels were very narrow; as the temperature was increased, the channels opened more and more, allowing gas molecules to move between the cages. A gas could move or become locked within the material depending on the size of […]