弧型波导全光开关的优化设计

应用光束传输法对基于三阶非线性材料的弧型波导全光开关的开关特性进行了模拟,对两波导中心距、宽度及其不对称性等几何参数对开关特性的影响进行了分析,并对其进行了优化设计。结果表明,优化设计后的弧型波导全光开关具有较低的平均开关功率、数值化多次开关特性,有着弱光非线性全光开关的应用前景。     

压力开关自动校准方法研究

为了解决由压力开关检测时间延迟所引起的测量误差,设计了一种基于压力开关切换误差的循环逼近比较的自动校准方法。研究影响压力开关自动校准的机理,构建循环逼近比较模型,确定了压力开关的切换误差与压力变化率的函数关系;通过模型方案,搭建自动校准系统,利用闭环反馈,实时调整压力变化率,获取切换值。实验结果表明:该自动校准方案减小了校准过程中压力变化率和延迟时间的影响,测量重复性提高了50%。     

The designs of a scalable optical packet switching architecture

Abstract

This paper proposes a new switching architecture to be used in all optical packet switching networks. The proposed switch is derived from an original 2 × ?2 two‐stage multi‐buffer switched delay line based optical switching node, known as an M‐Quadro node. By incorporating bypass lines into the M‐Quadro architecture and employing a novel switch control strategy, the optical packet switching node can effectively resolve packet contentions, thus reducing the packet deflection probability substantially. Furthermore, we show that such architecture is scalable for a generic multiple stages optical packet switch with a larger number of input/output ports.     

Holographic switch with a ferroelectric liquid-crystal spatial light modulator for a large-scale switch

A holographic switch with a ferroelectric liquid-crystal spatial light modulator is proposed for large switching systems such as those used in subscriber networks. Preliminary experiments have achieved a one-input, 48-output switch. The relationship between the power of the control-light source and the number of outputs is calculated; the results agree well with the experiment. The calculation suggests that 10384-output switching can be obtained with a 25-mW control-light source. It should therefore be possible to control a large-scale switch with low-power control-light sources.     

Combined ZVS?ZCS topology for high-current direct current hybrid switches: design aspects and first measurements

Power electronic switches have been considered for load switching ever since their invention. This is because semiconductor switches enable fast, arc-less, reliable and maintenance-free switching. The main disadvantages in relation to conventional switches (i.e. circuit breakers), however, are their sensitivity to transients, high on-state losses and the presence of leakage current. The advantages of both types of switches can be exploited by combining the semiconductor and the mechanical switch and thereby their disadvantages, arc formation and regular maintenance, can also be eliminated. For hybrid switches (HSs), both zero voltage switching (ZVS) and zero current switching (ZCS) are frequently used. A new hybrid switching topology has been developed where both ZVS and ZCS techniques are applied to the mechanical switch. The `symbiosis' between these solid-state switching techniques and a mechanical switch eliminates several of the disadvantages, resulting in a more reliable direct current (DC) HS that requires less maintenance. The first turn-off measurement (up to 5 kA) from a prototype that has been developed for a 3-kV DC grid is presented     

Switching kinetics of a Cu2S-based gap-type atomic switch

The switching time of a Cu(2)S-based gap-type atomic switch is investigated as a function of temperature, bias voltage, and initial off-resistance. The gap-type atomic switch is realized using a scanning tunneling microscope (STM), in which the formation and annihilation of a Cu-atom bridge in the vacuum gap between the Cu(2)S electrode and the Pt tip of the STM are controlled by a solid-electrochemical reaction. Increasing the temperature decreases the switching time exponentially with an activation energy of about 1.38 eV. Increasing the bias voltage also shortens the switching time exponentially, exhibiting a greater exponent for the lower bias than for the higher bias. Furthermore, faster switching has been achieved by decreasing the initial off-resistance between the Cu(2)S electrode and STM tip. On the basis of these results, we suggest that, in addition to the chemical reaction, the electric field in the vacuum gap plays a significant role in the operation of a gap-type atomic switch. This investigation advances our understanding of the operating mechanism of an atomic switch, which is a new concept for future electronic devices.     

Digital switching in the quantum domain

Presents a switching architecture such that digital data can be switched in the quantum domain. The proposed mechanism supports unicasting as well as multicasting, and is strict-sense nonblocking. In addition, with appropriate interface conversion, this architecture can also be used to switch classical information. This results in a quantum switch that can be used to build classical and quantum information networks. To present this idea, we define the connection digraph which can be used to describe the behavior of a switch at a given time, then we show how a connection digraph can be implemented using elementary quantum gates. Compared with a traditional space or time domain switch, the proposed switching mechanism is much more scalable. Assuming an n/spl times/n quantum switch, the space consumption grows linearly, i.e., O(n), while the time complexity is O(1) for unicasting, and O(log/sub 2/n) for multicasting. Based on these advantages, a high-throughput switching device can be built simply by increasing the number of I/O ports.     

128×128 three-dimensional MEMS optical switch module with simultaneous optical path connection for optical cross-connect systems

A 128×128 three-dimensional MEMS optical switch module and a switching-control algorithm for high-speed connection and optical power stabilization are described. A prototype switch module enables the simultaneous switching of all optical paths. The insertion loss is less than 4.6 dB and is 2.3 dB on average. The switching time is less than 38 ms and is 8 ms on average. We confirmed that the maximum optical power can be obtained and optical power stabilization control is possible. The results confirm that the module is suitable for practical use in optical cross-connect systems.     

From traditional wristwatch to smartwatch: Understanding the relationship between innovation attributes,switching costs and consumers' switching intention

Smartwatches are one of the most disruptive innovations of the past decade. However, these hi-tech gadgets fail to attract interest in the same way as smartphones, or tablet PCs. Despite optimistic market growth forecasts, smartwatches have not taken the place of traditional wristwatches until today, and the number of people who use traditional wristwatches outnumbered those who use smartwatches. This study is thus motivated to examine the factors that affect traditional wristwatch users' intentions to switch to smartwatches. Based on the Diffusion of Innovations Theory, a research model was developed involving perceived product lifetime, financial switching costs, and procedural switching costs. The proposed model was then empirically evaluated using survey data collected from 234 actual traditional wristwatch users about their perception of switching intentions to smartwatches. The findings revealed that relative advantage and financial switching costs significantly influence traditional wristwatch users’ behavioral intentions to switch to smartwatches. Furthermore, financial switching costs mediated the effects of relative advantage and perceived product lifetime on the switching intention. Surprisingly, perceived product lifetime, complexity, and procedural switching costs do not have direct impacts on switching intention.     

Free-space optical cross-connect switch by use of electroholography

An electrically controlled holographic switch is proposed as a building block for a free-space optical interconnection network. The switch is based on the voltage-controlled photorefractive effect in KLTN crystals at the paraelectric phase. It is built of electrically controlled Bragg gratings stored in the volume of the crystal. A compact switch that connects four high-speed fiber-optic communication channels with high efficiency is demonstrated experimentally. The switch performance is investigated and optimized. This switch is extremely attractive for cascaded switching arrays such as those found in multistage interconnect networks.     

All-optical switching in Pharaonis phoborhodopsin protein molecules

Low-power all-optical switching with pharaonis phoborhodopsin (ppR) protein is demonstrated based on nonlinear excited-state absorption at different wavelengths. A modulating pulsed 532-nm laser beam is shown to switch the transmission of a continuous-wave signal light beam at: 1) 390 nm; 2) 500 nm; 3) 560 nm; and 4) 600 nm, respectively. Simulations based on the rate equation approach considering all seven states in the ppR photocycle are in good agreement with experimental results. It is shown that the switching characteristics at 560 and 600 nm, respectively, can exhibit negative to positive switching. The switching characteristics at 500 nm can be inverted by increasing the signal beam intensity. The profile of switched signal beam is also sensitive to the modulating pulse frequency and signal beam intensity and wavelength. The switching characteristics are also shown to be sensitive to the lifetimes of$mmb pbf pR_bf M$and$mmb pbf pR_bf O$intermediates. The results show the applicability of ppR as a low-power wavelength tunable all-optical switch.     

Asynchronous transfer mode distribution network by use of an optoelectronic VLSI switching chip

We describe a new optoelectronic switching system demonstration that implements part of the distribution fabric for a large asynchronous transfer mode (ATM) switch. The system uses a single optoelectronic VLSI modulator-based switching chip with more than 4000 optical input-outputs. The optical system images the input fibers from a two-dimensional fiber bundle onto this chip. A new optomechanical design allows the system to be mounted in a standard electronic equipment frame. A large section of the switch was operated as a 208-Mbits/s time-multiplexed space switch, which can serve as part of an ATM switch by use of an appropriate out-of-band controller. A larger section with 896 input light beams and 256 output beams was operated at 160 Mbits/s as a slowly reconfigurable space switch.     

First principle study of the self‐switching characteristics of the guanine based single optical molecular switch using carbon nanotube electrodes

The switching property of an optical single molecular switch based on a single DNA molecule guanine with a single walled carbon nanotube electrode has been investigated using density functional theory along with non‐equilibrium Green''s function based first principle approach. The semi‐empirical model of this single bio‐molecular switch has been operated at an ultra‐high 25 THz frequency in mid‐UV range. This single bio‐molecule comprises switching activity upon UV photo‐excitation. The influence of the highest occupied molecular orbital and lowest unoccupied molecular orbital gap and the quantum ballistic transmission into the switching activity are discussed in detail in this study. It has been observed that the maximum ON–OFF ratio, i.e. 327 is obtained at +0.8 V bias voltage. Theoretical results show that current through the twisted form is sufficiently larger than the straightened form, which recommends that this structure has smart prospective application in the future generation switching nanotechnology.Inspec keywords: molecular electronic states, density functional theory, ab initio calculations, DNA, organic compounds, molecular electronics, Green''s function methods, molecular biophysics, single‐wall carbon nanotubes, optical switches, orbital calculationsOther keywords: nonequilibrium Green''s function, semiempirical model, single bio‐molecular switch, UV photo‐excitation, lowest unoccupied molecular orbital gap, first principle study, single optical molecular switch, switching property, optical single molecular switch, single DNA molecule guanine, single walled carbon nanotube electrode, density functional theory, highest occupied molecular orbital gap, switching nanotechnology     

Analysis and implementation of an active snubber dc/dc converter with series?parallel connection in primary and secondary sides

An active snubber dc/dc converter to achieve zero voltage switching (ZVS) on power switch is presented. In the proposed converter, the primary windings of two transformers are connected in series so that the primary currents of the two transformers are equal. The secondary sides of the isolated zeta converters are connected in the parallel to share the load current and reduce the current stresses on the secondary windings of the two transformers. A boost type of active snubber is connected in parallel with the main switch to recycle the energy stored in transformer leakage and magnetizing inductors and to limit voltage stress of the main switch. During the transition interval between the active switch and the auxiliary switch, the resonance based on the resonant inductor and the output capacitor of the power switch will allow the switch to turn on at ZVS. The principle of operation, steady-state analysis and design consideration of the proposed converter are provided. Finally, experimental results for a 360 W (12 V/30 A) prototype circuit with 150 kHz switching frequency were given to demonstrate the circuit performance and verify the feasibility of the proposed converter.     

Zero voltage switching active clamp buck-boost stage Cuk converter

The paper presents an active clamp buck-boost stage Cuk converter to achieve soft switching commutation. An auxiliary switch and a clamp capacitor are connected in parallel with the primary side of the transformer to absorb all the energy stored in the transformer leakage inductance. The resonant inductance and the clamp capacitance are resonant to achieve zero-voltage switching (ZVS) of the auxiliary switch. On the other hand, the resonance between the resonant inductance and output capacitance of the main switch will achieve ZVS of the main switch in the proposed converter. The principle of operation and system analysis are presented. Design considerations of the proposed converter are also provided. Experimental results for a 170 W prototype circuit operating at 70 kHz are given to demonstrate the effectiveness of the proposed converter     

Arc-shaped waveguide switch based on the third-order nonlinear effect

A kind of arc-shaped all-optical waveguide switch is proposed for the first time, to the best of our knowledge, and the switching characteristics of it are investigated by means of the beam propagation method. The effects of saturation and loss on the characteristics of the switch are discussed.     

Design,analysis and application of high set-up ZVT DC–DC converter with direct power transfer

In this paper, a new snubber cell for soft switched high set-up DC–DC converters is introduced. The main switch is turned on by zero-voltage transition and turned off by zero-voltage switching (ZVS). The main diode is turned on by ZVS and turned off by zero-current switching. Besides, all auxiliary semiconductor devices are soft switched. Any semiconductor device does not expose the additional current or voltage stress. The new snubber transfers some of the circulation energy to the output side when it ensures soft switching for main semiconductor devices. Thus, the current stress of auxiliary switch is significantly reduced. Besides, the total efficiency of converter is high due to the direct power transfer feature of new converter. A theoretical and mathematical analysis of the new converter is presented, and also verified with experimental set-up at 500 W and 100 kHz. Finally, the overall efficiency of new converter is 97.4% at nominal output power.     

A remotely controlled coaxial switch for impedance standard calibration

A switch which permits the connection, in sequence, of a couple of four-terminal-pair impedance standards to an automatic RLC bridge, is presented. The purpose of the switch is to automate the process of impedance calibration by 1:1 substitution. The switch is capable of engaging four coaxial lines at a time (switching both the internal conductor and the screen of each line); the electrical contacts are British Post Office MUSA connector. The switch, in the closed position, adds 2 m/spl Omega/ of resistance to each coaxial line in the electrical path. The switch is moved by pneumatic actuators to avoid any electrical interference, and is remotely controlled via RS-232 interface. Measurement examples are shown.     

Switching transient analysis of a metal/ferroelectric/semiconductor switch diode with high speed response to infrared light

A thin PbTiO(3)-n-p(+) silicon switch diode has been developed, in which the switching voltage (the turned-on voltage) changes in proportion to the infrared light power. The diode has a rapid response time of 0.65 mus compared with other conventional infrared sensors. It is attributed to the rapid switching device structure and the smaller pyroelectric layer thickness, 50 nm. In this paper, we have analyzed the rapid switching transient response by using heat conduction and switching theory successfully. The experimental results are in agreement with the theoretical analysis.