Integrated model for performance analysis of all-optical multihop packet switches

The overall performance of an all-optical packet switching system is usually determined by two criteria, i.e., switching latency and packet loss rate. In some real-time applications, however, in which packets arriving later than a timeout period are discarded as loss, the packet loss rate becomes the most dominant criterion for system performance. Here we focus on evaluating the performance of all-optical packet switches in terms of the packet loss rate, which normally arises from the insufficient hardware or the degradation of an optical signal. Considering both aspects, we propose what we believe is a new analysis model for the packet loss rate that reflects the complicated interactions between physical impairments and system-level parameters. On the basis of the estimation model for signal quality degradation in a multihop path we construct an equivalent analysis model of a switching network for evaluating an average bit error rate. With the model constructed we then propose an integrated model for estimating the packet loss rate in three architectural examples of multihop packet switches, each of which is based on a different switching concept. We also derive the bounds on the packet loss rate induced by bit errors. Finally, it is verified through simulation studies that our analysis model accurately predicts system performance.     

Performance evaluation of bufferless optical packet switches supporting quality of service

The author evaluates the performance of bufferless optical packet switches equipped with shared tuneable optical wavelength converters (TOWC) and supporting the quality of service (QoS). The TOWCs are shared per output fibre and, hence each output fibre has a dedicated pool of TOWCs. The TOWCs are not completely shared within the node. The QoS, expressed in terms of the packet loss probability, is differentiated by giving the packets different priorities in accessing both the output wavelengths and the TOWCs. A scheduling algorithm is proposed and its complexity is evaluated. The QoS technique?s effectiveness is studied by means of an analytical model based on a probabilistic approach and validated by simulation results. The results show that the proposed technique to support the QoS facilitates a good differentiation of the QoS offered to packets.     

Synchronous extraction of microwave energy from cavities through a packet of interference switches

Synchronous extraction of energy from cavity resonators for X-band microwave radiation through a compact packet of five interference switches based on H tees has been experimentally analyzed. It is shown that switches can be completely synchronized and the synchronization conditions are determined. Microwave pulses have been generated upon synchronous extraction of energy from five single-mode cavities (power ～0.8 MW, gain ～12 dB, and width ～3.2 ns) and from one superdimensional cavity (power ～2.2 MW, gain ～16.5 dB, and width ～3.5 ns). The operation limits of X- and S-band microwave compressors with extraction of energy through a packet are estimated.     

Heat switches for ADRs

Heat switches are key elements in the cyclic operation of Adiabatic Demagnetization Refrigerators (ADRs). Several of the types of heat switches that have been used for ADRs are described in this paper. Key elements in selection and design of these switches include not only ON/OFF switching ratio, but also method of actuation, size, weight, and structural soundness. Some of the trade-off are detailed in this paper.     

Concatenation performance of optical packet switches that incorporate wavelength converters based on four-wave mixing in semiconductor optical amplifiers

Four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) has been acknowledged as a useful wavelength conversion technique especially due to its ability to convert sequences of ultra fast pulses but also simultaneously a number of wavelengths. An analysis is used to investigate the concatenation performance of optical packet switch that incorporate wavelength or waveband converters based on FWM in SOAs.     

A method for protecting communicated information using neural-network detection

A method for protecting information transmitted via a communication channel is proposed. According to this method, data messaging is encoded by a change in the shape of pulse sequences and the messages are detected based on the neural-network method of signal identification. The efficiency of the method is analyzed in the case of multichannel transmitting of graphical information.     

Difference-of-Gaussian-Like Characteristics for Optoelectronic Visual Sensor

Architecture using a new nonlinear optoelectronic sensor has been developed to imitate the functions of the higher level visual cortex. The optoelectronic sensor developed in this work has the properties approximated by difference of Gaussian (DOG) functions. The properties are due to the negative photoinduced current (PIC) and the negative differential (ND) characteristics according to the forward bias voltage, which have been successfully obtained for layer structures with a charge-storage layer of InAs/GaAs short-period superlattice. By using the new sensors, an optoelectronic sensing circuit has been designed conceptually to imitate the functions of selectivity to orientation angle, motion-direction and length of slit light in visual cortex.     

Demonstration for an Optoelectronic Switching Network

Abstract

The concept for building a multistage switching network with optoelectronic components for several hundred parallel channels is investigated. The key components for an experiment are: laser arrays, microlens arrays, holographic optical permutation elements and a monolithic optoelectronic application specific integrated circuit with integrated photodetectors and electronic logic for switching. The demonstration presented in this contribution is a non-blocking and selfrouting shuffle exchange network implementing Batcher's sorting algorithm. It consists of three cascaded stages each having four parallel channels running at a clock rate of 1 MBit s^?1. Scaling towards larger number of channels and higher overall data throughput is considered.     

Optoelectronic transmitters for medical ultrasound transducers

Optoelectronics and fiber optics can be used to miniaturize and improve the flexibility of the transducer cable and transducer handle of medical diagnostic ultrasound scanners. The reduction in size has gained importance as 2-D array transducers with up to 1000 independent channels become accepted to improve diagnostic ultrasound images. The authors describe the analysis, design, fabrication and testing of a prototype silicon photoconductive semiconductor switch (PCSS). The monolithic silicon PCSS was used in combination with an infrared semiconductor diode laser with a fiber optic “pigtail” to shock excite and burst excite a 2-D array transducer element resonant at 2.5 MHz. Optically controlled voltage, current, and ultrasound pulses are compared to those from conventional electronic shock excitation and narrow band Doppler pulses. The optically triggered ultrasound pulse for single shock excitation produced 30 V spikes at the 2-D array element with a fall time of 200 nsec and a rise time of 2 μsec with a peak current through the transducer element of 34 mA. An optically produced burst of eight pulses at a frequency of 2.5 MHz produced 11 V spikes at the transducer with a fall time under 100 nsec and a rise time of approximately 300 nsec. The peak current per pulse was 25 mA through the transducer element. These results show the feasibility of applying optoelectronic technology to replace conventional electronic transmitter technology     

A LISP-based heuristic scheduler for automatic insertion in electronics assembly

Computer solutions have not made a very significant impact on scheduling problems. This reflects the fact that algorithmic solutions are often not appropriate for scheduling problems. Scheduling problems are more amenable to heuristic solution techniques. This paper describes a heuristic system for job scheduling in printed circuit board assembly. The main part of the system is written in Common LISP.     

Optoelectronic Electricity Meter for High-Voltage Lines

A new method has been developed for measuring the power on high-voltage lines. It involves determining the power directly on the high-voltage line and transmitting the measured values to the ground potential side by the aid of infrared light pulses. Two electromechanical counters at ground side, one for each direction of energy flow, record the transported electrical energy. The measuring error of the device is of the order of 0.2 percent. The small number of active electronic components should result in satisfactory reliability.     

Multi-radio packet scheduling for real-time packet traffic on general link layer

提出了一个能够为在通用链路层(GLL)上的实时分组业务提供QoS保障的多接入分组调度算法.首先设计了一个目标是在保障实时业务QoS的同时避免资源浪费的调度效用函数,该函数表示将一个用户数据包调度到一个无线接入链路上进行传输所带来的效用;其次在这个调度函数的基础之上兼顾了公平性,建立一个多接入分组调度模型,值得注意的是该模型是一个NP问题;最后利用Hopfield神经网络来快速有效地为这个调度模型找出优化解.仿真结果表明,与M-LWDF和PLR等典型算法相比,该算法在高系统负载的情况下能够满足实时分组的时延要求,同时提高了频谱效率并降低了丢包率及时延抖动.     

An interactive scheduler for a wafer probe centre in semiconductor manufacturing

This paper analyses production operations and scheduling constraints on a wafer probe centre in semiconductor manufacturing. Such actions as lot split and hot lot preemption are discussed. Due to the combinatorial difficulties of scheduling problems with sequence-dependent setup costs and multiple criteria, a humancomputer interactive scheduler named the 'interactive computer aided scheduling system' (ICASS) is proposed. This ICASS can search for schedules to achieve a specific performance level set by a human. An experiment was conducted on a wafer probe centre to compare the performance of ICASS with that of a manual approach and six priority rules. The results indicate that ICASS spent less scheduling time and provided better schedules than the manual approach. All the six priority rules yielded only poor schedules with unbalanced performance in three kinds of criteria, although they were beneficial in computation time.     

2D Organic Materials for Optoelectronic Applications

The remarkable merits of 2D materials with atomically thin structures and optoelectronic attributes have inspired great interest in integrating 2D materials into electronics and optoelectronics. Moreover, as an emerging field in the 2D‐materials family, assembly of organic nanostructures into 2D forms offers the advantages of molecular diversity, intrinsic flexibility, ease of processing, light weight, and so on, providing an exciting prospect for optoelectronic applications. Herein, the applications of organic 2D materials for optoelectronic devices are a main focus. Material examples include 2D, organic, crystalline, small molecules, polymers, self‐assembly monolayers, and covalent organic frameworks. The protocols for 2D‐organic‐crystal‐fabrication and ‐patterning techniques are briefly discussed, then applications in optoelectronic devices are introduced in detail. Overall, an introduction to what is known and suggestions for the potential of many exciting developments are presented.     

Low-stress permalloy for magnetic MEMS switches

The residual stress in the electroplated magnetic films is an important factor that limits the functionality of many micromagnetic devices. We have investigated the stress in electroplated Ni-Fe alloy for MEMS as a function of bath concentration, utilizing the wafer-bending method. Our investigation demonstrated that a low-concentration plating solution decreases the residual stress in the electrodeposits, and the stress is further decreased by increasing the saccharin additive content. We obtained the low-stress Permalloy Ni/sub 81/Fe/sub 19/ in our experimental conditions. We fabricated a bistable electromagnetic RF MEMS switch with deformation-free cantilever beam using the electroplated Permalloy.     

An Optoelectronic Switch for Low-Level Analog Applications

This paper discusses characteristics and applications of an analog switch based upon the back-to-back connection of two light-emitter/phototransistor assemblies, with an original method of zeroing the offset voltage. The resulting device is thoroughly analyzed, and it is shown how this solid-state switch is comparable in accuracy with electromechanical relays, but it has much higher repetition-rate capabilities. Two applications are then introduced, namely an analog commutator and a low-level multiplexer, where the performances of the switch find their best exploitation.