Gain-shifted thulium-doped fibre amplifiers employing novel highconcentration doping technique

A novel high thulium concentration doping technique is proposed for shifting the gain band in thulium-doped fibre amplifiers (TDFAs). The gain peak shifts from 1473 to 1505 nm when the Tm³⁺ concentration is increased from 2000 to 8000 ppm. The authors have achieved gains of >18 dB and a noise figure (NF) of <7 dB from 1480 to 1510 nm (30 nm bandwidth) for a total pump power of 500 mW     

48% power conversion efficiency in single pump gain-shiftedthulium-doped fibre amplifier

A new pumping scheme (1.2 μm+1.4 μm) is demonstrated for a gain-shifted thulium-doped fibre amplifier (TDFA), leading to record efficiency of 48% using one single pump dual-wavelength laser     

Three-phase power frequency conversion with high efficiency and high spectral purity

It is shown that a pulse-width modulation circuit may be made to approach ideal product-modulator behaviour at low frequencies. The output of such a modulator contains sum and difference-frequency components: it is shown that the sum-frequency components may be made to cancel each other out completely in a 3-phase system.     

67% CW power conversion efficiency from Al-free 1060 nm emitting diode lasers

1060 nm emitting broad-waveguide-type aluminium-free diode lasers have been optimised for maximum power conversion efficiency (PCE). PCE at 67% is achieved at continuous-wave operation and 25degC heatsink temperature from a 1 mm cavity length, 100 mum stripe diode laser. The improvement is mainly the result of an increase in injection efficiency via optimisation of the bandgap structure, and reductions in operating voltage via doping optimisation of the broad-waveguide structure.     

1 V power supply, low-power consumption A/D conversion techniquewith swing-suppression noise shaping

A 1 V power supply and low-power consumption A/D conversion technique using swing-suppression noise shaping is proposed. This technique makes it possible to power the on chip A/D converter in digital LSI's directly by a one-cell battery, without a dc-dc converter. Experimental results indicated good performance for the RF-to-baseband analog interface of a digital cordless phone. The A/D converter, fabricated with a 0.5 μm CMOS process, operates on a 1 V power supply, has a 10 bit dynamic-range with a 384 ksps sampling speed and consumes only 1.56 mW     

Enhancing power conversion efficiency of DSSC by doping SiO2 in TiO2 photo anodes

A simple, less time consuming, cost ineffective sol–gel method was used to synthesis TiO₂ nanoparticles (TiO₂) and TiO₂–SiO₂ nanocomposites (TiO₂–SiO₂) using titanium tetra isopropoxide as TiO₂ and silicic acid as SiO₂ precursors respectively. The synthesized nanocomposites were characterized by XRD, SEM, TEM, UV–visible, FTIR and BET analysis. The quantum confinement effect of TiO₂ and TiO₂–SiO₂ was confirmed by a blueshift observed in UV–visible spectra. The band observed at 950 cm⁻¹ in FTIR analysis confirmed the presence of Ti–O–Si bonds, the TEM analysis shows both the TiO₂ and TiO₂–SiO₂ were in nanometer size. The BET (Brunauer– Emmett–Teller) specific surface areas of the samples were 65 and 75 m²/g for TiO₂ and TiO₂–SiO₂ respectively. The power conversion efficiency (PCE) of the nanocomposites were studied by using Keithely electrometer and multimeter and it was found to be 2% and 2.5% for eosin-Y sensitized TiO₂ and TiO₂–SiO₂ nanocomposites respectively.     

Ultra-high-power quasi-CW monolithic laser diode arrays with high power conversion efficiency

An optical power output of 134 W from one facet and power conversion efficiencies as high as 49% have been obtained from monolithic AlGaAs laser arrays with 1 cm emitting widths for 150^s pulse widths (quasi-CW operation). The arrays have etched grooves to prevent transverse lasing and amplified spontaneous emission.     

Very high CW output power and power conversion efficiency from current-confined CDH-LOC diode lasers

CDH-LOC lasers with tight current confinement to the lasing region provide CW output powers as high as 165 mW. The overall power conversion efficiency in CW operation reaches values of 35% (front-facet emitted power/overall input electrical power). Single-longitudinal-mode and fundamental-mode operations are achieved to 40 mW CW and 60 mW peak power (50% duty cycle), respectively. The threshold-current temperature coefficient T0 reaches values of 185 K.     

三洋研发成功提高镍氢电池容量的新技术

精工爱普生开发成功传输效率高达约70%的非接触式电源传输模块.此模块是利用电磁感应原理,从输电端模块向受电端模块传输电能而无需通过触点.输电端模块集成了初级线圈和线圈的驱动电路等,充电端模块则集成了次级线圈和二极管整流器、滤波电容器.此项技术将应用于个人数字助理(PDA)和手机等的蓄电池充电及工业用传感器非接触式供电等领域.     

Ti∶Mg∶LiNbO_3晶体70%转换效率的二次谐波发生

本文报道用提拉法生长的掺钛掺镁铌酸锂晶体(Ti∶Mg∶LiNbO_2)用于Q开关Nd:YAG激光器1.06μm辐射的腔外倍频,在单通情况下得到了高达70％的转换效率;而在双通情况下,转换效率为81％。     

A new inverter-based charge pump circuit with high conversion ratio and high power efficiency

The current paper presents a new inverter-based charge pump circuit with high conversion ratio and high power efficiency. The proposed charge pump, which consists of a PMOS pass transistor, inverter-based switching transistors, and capacitors, can improve output voltage and conversion ratio of the circuit. The proposed charge pump was fabricated with TSMC 0.35 μm 2P4M CMOS technology. The chip area without pads is only 0.87 mm×0.65 mm. The measured results show that the output voltage of the four-stage charge pump circuit with 1.8 V power supply voltage (V_DD=1.8 V) can be pumped up to 8.2 V. The proposed charge pump circuit achieves efficiency of 60% at 80 μA.     

Electrodeposited Cu2ZnSnSe4 thin film solar cell with 7% power conversion efficiency

High performance Cu₂ZnSnSe₄ (CZTSe) photovoltaic materials were synthesized by electrodeposition of metal stack precursors followed by selenization. A champion solar cell with 7.0% efficiency is demonstrated. This is the highest efficiency among all of the CZTSe solar cells prepared from electrodeposited metallic precursors reported to‐date. Device parameters are discussed from the perspective of material microstructure and composition in order to improve performance. In addition, a high performance electrodeposited CZTS (S only) solar cell was demonstrated and its device characteristics were compared against the CZTSe (Se only) cell. Using secondary ion mass spectrometry for the analysis of the chemical composition of the absorber layer, a higher concentration of oxygen in the electrodeposited absorber is thought to be the root cause of the lower performance of the electrodeposited CZTS or CZTSe solar cells with respect to a solar cell fabricated by evaporation. The grain boundary areas of Sn‐rich composition are thought to be responsible for the lower shunt resistance commonly observed in CZTSe devices. We measured the longest minority carrier lifetime of 18 ns among all reported kesterite devices. This work builds a good baseline for obtaining higher efficiency earth‐abundant solar cells, while it highlights electrodepositon as a low cost and feasible method for earth‐abundant thin film solar cell fabrication. Copyright © 2013 John Wiley & Sons, Ltd.     

73% CW power conversion efficiency at 50 W from 970 nm diode laser bars

970 nm emitting diode laser bars of broad-waveguide design have been optimised for maximum power conversion efficiency (PCE). 73% PCE at 50 W CW output power is achieved from 20% fill-factor, 1 cm diode laser bars mounted on microchannel-cooled heatsinks. The improvement is mainly the result of an increase in injection efficiency via moderately low doping of the broad-waveguide core, and reductions in operating voltage via doping optimisation of the broad-waveguide structure.     

满足更高能量转换效率的要求新型IC帮助克服传统拓扑的局限

能耗是非常热门的话题,能量转换也因此具有更加重要的意义.电子设备已经成为我们日常生活中必不可少的一部分,减少这些设备的能耗将具有非常重要的意义.     

Highly efficient bifacial transparent organic solar cells with power conversion efficiency greater than 3% and transparency of 50%

In this work, we present vacuum-deposited bifacial transparent organic solar cells on indium-tin-oxide-coated glass substrates. Good performances and high transparencies are achieved simultaneously by employing the planar-mixed heterojunction of the organic donor 2-{[7-(5-N,N-ditolylaminothiophen-2-yl)-2,1,3-benzothiadiazol-4-yl]methylene}malononitrile (DTDCTB) and fullerenes with carefully designed resonance top electrodes. Comprehensive optical simulation is exploited to investigate the effect of the top-electrode configuration on the cell transparency and efficiency. Cells with structures designed for high transparencies were fabricated and tested. The DTDCTB:C₆₀ device yields a high transmission of up to 66.4% at 530 nm and a power conversion efficiency (PCE) of 2.11%. Moreover, the DTDCTB:C₇₀ device demonstrates an exceptional PCE as high as 3.24% with a balanced transmission of ≈50% in the visible spectrum. Enhanced PCE values of transparent solar cells are also revealed with the use of external reflectors. Efficiency enhancements of ≈15% and ≈65% are achieved by simply attaching a reflection mirror at the cathode or anode side, respectively.     

High single-mode power conversion efficiency vertical-cavitytop-surface-emitting lasers

We report advances in the power conversion (wall-plug) efficiency of vertical-cavity top-surface-emitting lasers. The devices were fabricated from molecular beam epitaxial layers using deep proton implants to define gain-guided lasers. The epitaxial structure included low resistance, piecewise linearly graded n-type and p-type mirrors, a triple In_0.2Ga_0.8As quantum-well active region, and a delta-doped contact layer. Power conversion efficiencies as high as 12.7% for continuous-wave single-mode operation were measured after several hours of device operation     

High optical-optical efficiency of 52.5% obtained in high power Nd:YAG ceramic laser

Using a quite uniformly side-around arranged compact pumping system, a high power Nd:YAG ceramic quasi-CW laser has been demonstrated with high optical-to-optical conversion efficiency over 50% for the first time. With 450 W quasi-CW stacked laser diode bars pumping at 808 nm, 236 W output at 1064 nm was obtained and no saturation phenomena were observed     

Effects of doping profile on the conversion efficiency of a Gunn diode

A large-signal computer simulation was made for several simplified nonuniform doping profiles that correspond to those of practicalX-band Gunn diode. Maximum available dc-to-RF conversion efficiency was searched for each profile by varying the oscillation frequency and the magnitude of the RF terminal voltage while the dc bias was fixed. The result showed that a higher-resistance cathode-side region degrades the efficiency mainly through decrease of the amplitude of the RF current, while a higher resistance anode-side region degrades the efficiency much more by delaying the phase of the domain nucleation. An improvement of the efficiency by about 20 percent was found to be possible by introducing a low-resistance region near the anode to deform the RF current waveform. Computations were also made for several nonuniform profiles that were observed experimentally. Calculated and experimental results were compared, and reasonable agreement between the two was found, though there were some cases in which the agreement was not obtained due to nonideal properties of electrode boundaries.     

光纤喇曼放大器的功率转换效率分析

在定义光纤喇曼放大器(FRA)功率转换效率(PCE)的基础上,考察了不同工作条件下光纤喇曼放大器的功率转换效率,分析PCE与光纤喇曼放大器的输入信号功率、输入泵浦功率和光纤长度的关系,比较了分布式与集总式FRA的功率转换效率,给出提高FRA功率转换效率的途径。     

Simplified processing for high spectral efficiency wirelesscommunication employing multi-element arrays

We investigate robust wireless communication in high-scattering propagation environments using multi-element antenna arrays (MEAs) at both transmit and receive sites. A simplified, but highly spectrally efficient space-time communication processing method is presented. The user's bit stream is mapped to a vector of independently modulated equal bit-rate signal components that are simultaneously transmitted in the same band. A detection algorithm similar to multiuser detection is employed to detect the signal components in white Gaussian noise (WGN). For a large number of antennas, a more efficient architecture can offer no more than about 40% more capacity than the simple architecture presented. A testbed that is now being completed operates at 1.9 GHz with up to 16 quadrature amplitude modulation (QAM) transmitters and 16 receive antennas. Under ideal operation at 18 dB signal-to-noise ratio (SNR), using 12 transmit antennas and 16 receive antennas (even with uncoded communication), the theoretical spectral efficiency is 36 bit/s/Hz, whereas the Shannon capacity is 71.1 bit/s/Hz. The 36 bits per vector symbol, which corresponds to over 200 billion constellation points, assumes a 5% block error rate (BLER) for 100 vector symbol bursts