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We report the effects of hydrostatic pressure up to p~1.73GPa on the multiferroic and magnetoelectric properties of GdMn2O5 single crystals. The ferroelectric (FE) polarization can be enhanced at low pressures, while it decreased after reaching a maximum at p~1.30 GPa. This pressure induced variation of polarization can be ascribed to the combined results of Mn-Mn and Gd-Mn exchange striction under pressure. Our results show that the polarization induced by Mn-Mn interaction increases monotonously with increasing pressure and finally saturates above p≥1.30GPa. Interestingly, we find that a new FE phase appears in the temperature range of 31K-38K with pressure p≥0.88GPa. This new FE phase can be suppressed by magnetic field, but stabilized by pressure. The pressure-temperature (p-T) phase diagram of GdMn2O5 was obtained. Our analyses suggest that the pressure-induced new FE phase could arise from a non-collinear, incommensurate magnetic structure. [ABSTRACT FROM AUTHOR]

We report the effects of hydrostatic pressure up to p~1.73GPa on the multiferroic and magnetoelectric properties of GdMn2O5 single crystals. The ferroelectric (FE) polarization can be enhanced at low pressures, while it decreased after reaching a maximum at p~1.30 GPa. This pressure induced variation of polarization can be ascribed to the combined results of Mn-Mn and Gd-Mn exchange striction under pressure. Our results show that the polarization induced by Mn-Mn interaction increases monotonously with increasing pressure and finally saturates above p≥1.30GPa. Interestingly, we find that a new FE phase appears in the temperature range of 31K-38K with pressure p≥0.88GPa. This new FE phase can be suppressed by magnetic field, but stabilized by pressure. The pressure-temperature (p-T) phase diagram of GdMn2O5 was obtained. Our analyses suggest that the pressure-induced new FE phase could arise from a non-collinear, incommensurate magnetic structure. [ABSTRACT FROM AUTHOR]

The effects of Zn-phosphate coating on the magnetic properties of Fe73.5Cu1Nb3Si15.5B7 nanocrystalline alloy powder cores have been investigated. The Zn-phosphate coating provided good electrical insulation between the magnetic particles through formation of an oxide and other compounds on their surfaces. The consolidated magnetic cores with powders treated in the solution of pH=1.3 acidity exhibited a permeability of 45, persisting up to about 2 MHz and a core loss of 500 mW/cm3 at the frequency of 50 kHz under the induction of Bm=0.1 T. Furthermore, 62% permeability at 50 Oe of dc bias field was obtained. From these results, it was considered that the Zn-phosphate coating could be an effective method to form an efficient insulating coat even for small-sized Fe73.5Cu1Nb3Si15.5B7 nanocrystalline alloy powders. [ABSTRACT FROM AUTHOR]

Semicooled operation at 40°C of electroabsorptive modulator integrated laser (EML) for intermediate reach communication has been demonstrated. Reproducible operation at the elevated temperature was achieved through a device parameter optimized based on the temperature dependence of the dc characteristics of EML and a design of multi-quantum-well structure providing both relevant output power and high-frequency bandwidth at 40°C. Good eye pattern and near zero chirp with the average power over 0 dBm are obtained at 40°C, with an estimated lifetime over 20 years. [ABSTRACT FROM PUBLISHER]

A new high efficiency Doherty structure for code division multiple access 2000 1×3-FA test signal is presented. The proposed Doherty structure consists of a two-stage symmetric Doherty drive amplifier and an inverted asymmetric Doherty power amplifier. This Doherty structure can improve the efficiency characteristic and reduce the amplifier's dimensions. Also, higher-order intermodulation distortion products can be self-compensated. For demonstration of the amplifier's performance, a 74 W Doherty amplifier has been simulated and measured. [ABSTRACT FROM AUTHOR]

The effects of growth pressure in metal-organic chemical vapor deposition (MOCVD) on the structural and optical properties of InGaN/GaN multiple-quantum-wells (MQWs) grown on c-plane sapphire substrate were investigated by scanning transmission electron microscopy (STEM), atom probe tomography (APT), Raman spectroscopy and electroluminescence (EL) spectroscopy. As the growth pressure decreased, the growth rate of the InGaN layer increased, leading to a decrease in the frequency of the GaN A1(LO) mode peak and broadening of its full width half maximum (FWHM). The intensity of the EL spectra peaked at a growth pressure of 250 Torr with a narrow FWHM at high forward current. These optical properties are explained by either a high degree of compositional fluctuation of indium in the MQW and/or the high crystallinity of the InGaN layer due to the low growth rate under high pressure., (Copyright © 2012. Published by Elsevier B.V.)

A mode-locked fiber laser gyroscope is reported that uses a distributed-feedback semiconductor laser amplif ier as the gain medium. Stable mode-locked optical pulses were obtained without gain competition, and the pulse interval could be measured with much-improved accuracy as a function of rotation rate. The rms noise equivalent rotation rate was measured to be 0.4 deg/ radicalh.