Search

Single-crystal diamond (SCD) detectors show promise as neutron spectrometers. They have been increasingly used for neutron monitoring of high-flux deuterium plasmas. In this article, a high-performance SCD detector is exposed to D-T neutrons at different angles to measure the energy spectra. The results show that the diamond detector is stable under neutron irradiation fluence of $1.63\times10$ 10 n/cm2 during the 2 h testing. Its detection efficiency for 12C (n, $\alpha$) 9Be is (3.31 ± 0.11) $\times \,\, 10$ −4 counts/n, which is in good agreement with a Monte Carlo simulation predicted by a Geant4 simulation. The deviation in the detection efficiency between the simulation and experimental results is as low as 0.61%. In addition, a response matrix is created and Gaussian broadening has been applied to obtain a good alignment between the measured and simulated results. Finally, a variety of neutron spectrum unfolding methods, namely, the non-negative least-squares algorithm, the Gravel algorithm, the Gold algorithm, and the Lucy–Richardson algorithm, are applied and compared in detail, demonstrating that using a SCD detector, the precise energy distribution of the D-T neutrons from different angles can be obtained by exploiting the spectrum unfolding methods. [ABSTRACT FROM AUTHOR]

This brief presents a 64-channel fully-integrated wireless neural interfacing SoC implemented in a 65 nm CMOS process. To minimize the weight and size of the head-stage connected to the small experimental animals, the system is designed to be powered by either a single-coil 13.56 MHz wireless power receiver or a small-sized button cell battery. A replica-biased 0.35 V 110 dB PSRR LNA is introduced to tolerate the power supply noise inherently in wireless power harvesting and save power consumption. The recorded neural data is transmitted wirelessly by a 2.4/3.2 GHz dual-band OOK transmitter, which supports 54 Mb/s symbol rate, 44 pJ/bit meter-range wireless data transmission. To reduce the transmission BER, forward error correction with convolutional code and cyclic redundancy code is adopted. [ABSTRACT FROM AUTHOR]

A novel approach to generating microwave frequency shift keying (FSK) signals using a polarization modulator (PolM) and a dual-polarization Mach–Zehnder modulator (DPol-MZM) is proposed and experimentally demonstrated. In the proposed system, the PolM is employed to modulate the polarization state of an input linearly polarized lightwave to switch between two orthogonal directions, leading to the generation of a polarization shift keying (PolSK) signal. Then the PolSK signal is sent to a DPol-MZM, which is made up of two polarization multiplexed sub-MZMs by a polarization controller (PC). Two microwave signals with different frequencies are applied to the sub-MZMs. After aligning the orthogonal directions of the PolSK signal with the axes of the DPol-MZM by the PC, the PolSK signal can be converted into a microwave FSK signal. A proof-of-concept experiment is carried out to verify the proposed system. When the sub-MZMs in the DPol-MZM are biased at a quadrature point, a double sideband microwave FSK signal at 3/6.5 GHz with a bit rate of 1.25 Gb/s is generated and transmitted over 10 km of single-mode fiber. When the sub-MZMs are biased at minimum point, an optical carrier suppression microwave FSK is achieved at frequency-doubled 6/14 GHz with a bit rate of 2.5 Gb/s. [ABSTRACT FROM PUBLISHER]

A novel scheme for the generation of full-duty-cycle triangular pulses based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The fundamental tone corresponding to the repetition rate of the pulses is generated by the OEO. Biasing the Mach–Zehnder modulator at the quadratic point, the small-signal gain of the OEO is maximized, while even-order harmonics in the optical intensity are suppressed. By properly setting the gain of the OEO loop, the amplitude of the first-order harmonic is nine times that of the third-order harmonic. After a 90° electrical phase shifter adjusts the phase of the electrical signal at the output of the photodetector, triangular pulses are obtained in the time domain. The oscillating frequency is tuned from 2 to 10 GHz by the yttrium-iron-garnet filter, and the phase noise of generated signal is also investigated. Triangular pulses with repetition rates of 3 and 6 GHz are successfully generated. The root-mean-square errors between the generated and the ideal triangular waveforms are 6.4927e-4 and 9.0932e-4 at 3 and 6 GHz, respectively. [ABSTRACT FROM PUBLISHER]

Some nonvolatile phase change memory (PCM) cells with 80-nm heating electrodes are found very difficult to RESET at 3 mA, which directly affects the RESET distribution of the PCM. The large crystal grains with hexagonal structure in the active phase change area, discovered by transmission electron microscope, are the major reason. One preprogramming testing method is introduced, and the resistance distributions of the PCM cells before and after preprogramming are presented. Results show that the large hexagonal crystal grains have been eliminated, thus the resistance distributions have been greatly improved after preprogramming. [ABSTRACT FROM AUTHOR]

Polygonal GaN sidewalls are fabricated using a laser scriber and a wet-etching process. After a two-step laser scribing process and a hot acid etching treatment, curved GaN sidewalls are formed consisting of the chemically stable (10-1-2) crystallographic plane of GaN epilayer and the laser-cutting facets. Compared to light-emitting diodes (LEDs) with vertical and inclined GaN sidewalls, light output power of LEDs with these curved GaN sidewalls exhibits an improvement of 10.2% and 6.8%, respectively. I-V curve shows that there is no deterioration to the curved-sidewall LEDs' electronic properties. This enhancement of light output power is also confirmed by numerical simulations using the ray-tracing method. [ABSTRACT FROM PUBLISHER]