Terabit optical local area networks for multiprocessing systems

The design of a scalable optical local area network formultiprocessing systems is described. Each workstation has aparallel-fiber-ribbon optical link to a centralized complementarymetal-oxide silicon (CMOS) switch core, implemented on a singlecompact printed circuit board (PCB). When the Motorola Optobusfiber technology is used, each workstation has a data bandwidth of 6.4Gbits/s to the core. A centralized switch core interconnecting 32workstations supports a 204-Gbit/s aggregate data bandwidth. Theswitch core is based on a conventional broadcast-and-selectarchitecture, implemented with parallel CMOS integrated circuits(IC's). The switch core scales well; by incorporation of theCMOS optoelectronic IC's with optical input-output, the electricalcore can be reduced to a single-chip optoelectronic IC with terabitcapacities. A prototype of an optoelectronic switch core has been fabricated and is described. The appeal of the architectureincludes its reliance on commercially available parallel-fibertechnology, its reliance on the well-developed markets of local areanetworks and networks of workstations, and its smooth scalability from the electrical to optical domains as technology matures.     

Experimental demonstration of the optical multi-mesh hypercube: scaleable interconnection network for multiprocessors and multicomputers

A prototype of a novel topology for scaleable optical interconnection networks called the optical multi-mesh hypercube (OMMH) is experimentally demonstrated to as high as a 150-Mbit/s data rate (2(7) - 1 nonreturn-to-zero pseudo-random data pattern) at a bit error rate of 10(-13)/link by the use of commercially available devices. OMMH is a scaleable network [Appl. Opt. 33, 7558 (1994); J. Lightwave Technol. 12, 704 (1994)] architecture that combines the positive features of the hypercube (small diameter, connectivity, symmetry, simple routing, and fault tolerance) and the mesh (constant node degree and size scaleability). The optical implementation method is divided into two levels: high-density local connections for the hypercube modules, and high-bit-rate, low-density, long connections for the mesh links connecting the hypercube modules. Free-space imaging systems utilizing vertical-cavity surface-emitting laser (VCSEL) arrays, lenslet arrays, space-invariant holographic techniques, and photodiode arrays are demonstrated for the local connections. Optobus fiber interconnects from Motorola are used for the long-distance connections. The OMMH was optimized to operate at the data rate of Motorola's Optobus (10-bit-wide, VCSEL-based bidirectional data interconnects at 150 Mbits/s). Difficulties encountered included the varying fan-out efficiencies of the different orders of the hologram, misalignment sensitivity of the free-space links, low power (1 mW) of the individual VCSEL's, and noise.     

VCSEL-array-based angle-multiplexed optoelectronic crossbar interconnects

A large crossbar switch, which is a desirable building block for any low-latency interconnect network, is difficult to implement because of many practical problems associated with digital electronics. We propose a new method for implementing a large optoelectronic crossbar interconnect to take advantage of a unique principle of optics. Based on an emerging vertical-cavity surface-emitting laser (VCSEL) technology, a passive angle-multiplexed beam-steering architecture is proposed as a key component of the optoelectronic crossbar. Various optical system parameters are evaluated. Because there is no optical fan-out power loss, the interconnect capacity of the proposed system is determined by the diffraction-limited receiver power cutoff, and therefore interconnection of more than 1000 nodes with a per node bandwidth of 1 GHz is possible with today's technology. A 64-element VCSEL-array-based proof-of-principle optical system for studying the interconnect scalability has been built. Details of the features of the proposed system, its advantages and limitations, demonstration experimental results, and their analyses are presented.     

高速850/980 nm垂直腔面发射激光器的研究进展

垂直腔面发射激光器(VCSEL)具有低损耗、 光束质量好、 光纤耦合效率高、 调制速率高且易于与其他光电子器件集成等优势,在光互连、 光存储、 高速传输和通讯等领域得到了迅猛发展.随着大数据时代的到来,对建立高带宽、 低损耗的高速光通讯网络提出了更高的要求.因此,近年来VCSEL在面向高速数据通讯中提高调制速率、 降低...     

Infrared single-mode fiber-optic Fourier-transform spectrometry and double Fourier interferometry

An infrared single-mode fiber-optic Fourier-transform spectrometer constructed for the demonstration of the technique is described, in which beam splitting and beam combining are performed with fiber-optic directional couplers and the optical path difference scan is generated by stretching fibers. Experiments done with this fiber-optic Fourier-transform spectrometer are presented. A spectral resolution of 1328 at 2.2 μm can be achieved. The experimental results show the feasibility of fiber-optic Fourier-transform spectrometry and double Fourier interferometry.     

高分辨率多屏平动体积显示系统

描述了一种基于多屏平动扫描的高分辨率体积显示系统及其原理样机。通过 DMD向多个圆周平动的成像屏投射二维图像序列,借助人眼视觉暂留效应,此动态刷新的二维图像序列被感知为一个具有物理景深的三维图像。其光学投影模块保证了投影仪与成像屏之间的光程不变,从而构建了清晰稳定的成像空间;采用 FPGA设计高速数据通道,带宽达到了 18.75 Gbps,使得每个三维体积帧包含 512个二维图像切片,总体素超过 4亿,刷新频率达到 12 Hz。成功研制了原理样机,达到了预期的三维显示效果。     

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.     

Three-dimensional optoelectronic stacked processor by use of free-space optical interconnection and three-dimensional VLSI chip stacks

We present a demonstration system under the three-dimensional (3D) optoelectronic stacked processor consortium. The processor combines the advantages of optics in global, high-density, high-speed parallel interconnections with the density and computational power of 3D chip stacks. In particular, a compact and scalable optoelectronic switching system with a high bandwidth is designed. The system consists of three silicon chip stacks, each integrated with a single vertical-cavity-surface-emitting-laser-metal-semiconductor-metal detector array and an optical interconnection module. Any input signal at one end stack can be switched through the central crossbar stack to any output channel on the opposite end stack. The crossbar bandwidth is designed to be 256 Gb/s. For the free-space optical interconnection, a novel folded hybrid micro-macro optical system with a concave reflection mirror has been designed. The optics module can provide a high resolution, a large field of view, a high link efficiency, and low optical cross talk. It is also symmetric and modular. Off-the-shelf macro-optical components are used. The concave reflection mirror can significantly improve the image quality and tolerate a large misalignment of the optical components, and it can also compensate for the lateral shift of the chip stacks. Scaling of the macrolens can be used to adjust the interconnection length between the chip stacks or make the system more compact. The components are easy to align, and only passive alignment is required. Optics and electronics are separated until the final assembly step, and the optomechanic module can be removed and replaced. By use of 3D chip stacks, commercially available optical components, and simple passive packaging techniques, it is possible to achieve a high-performance optoelectronic switching system.     

System integration and radiation pattern measurements of a phased array antenna employing an integrated photonic beamformer for radio astronomy applications

In this paper we describe the system integration and the experimental demonstration of a photonically beamformed four-element receiving array antenna for radio astronomy applications. To our knowledge, the work described here is the first demonstration of the squint-free, continuously tunable beamsteering capability offered by an integrated photonic beamformer based on optical ring resonator true-time-delay units, with measured radiation patterns. The integrated beamformer is realized in a low loss, complementary metal-oxide-semiconductor (CMOS) compatible optical waveguide technology. The measurements show a wideband, continuous beamsteering operation over a steering angle of 23.5 degrees and an instantaneous bandwidth of 500 MHz limited only by the measurement setup.     

Waveform-synthesis method that reduces battery power in an electrically small wideband radiating system

An electrically small antenna is extremely inefficient when operating over a large (multi-octave) bandwidth in a conventional radiating system. As a result, a large amount of prime battery power would be needed to generate sufficient radio frequency (RF) signal power to overcome the poor antenna efficiency and to induce the desired amount of radiation. An alternative method is described in which electronic switches are integrated within a small loop antenna. The switches operate at a rate greater than the RF carrier frequency and are used to synthesise the desired RF current waveform that passes through the loop. This switching circuit replaces the power amplifier in a conventional radiating system. The battery power needed to stimulate a given radiated signal strength is significantly less [a factor of 1/10 at very high frequency (VHF)] compared with the traditional wideband power amplifier/antenna system. The performance of a prototype VHF system is described.     

CMOS multiplier based on the relationship between drain current and inversion charge

The authors propose a four-quadrant multiplier based on a core cell that exploits the general relationship between the saturation current of an MOS transistor and the source inversion charge density, valid from weak to strong inversion. The advantages of the proposed circuit are simplicity, low distortion and feasibility of low-voltage operation. Experimental results in a 0.35 μm CMOS prototype indicate 1 mA consumption for 1 MHz bandwidth, and distortion level below 1% for an input current of 80% of the full-scale range. The multiplier core area is around 10 000 mm².     

Power-efficient dual-rate optical transceiver

A dual-rate (2 Gbit/s and 100 Mbit/s) optical transceiver designed for power-efficient connections within and between modern high-speed digital systems is described. The transceiver can dynamically adjust its data rate according to performance requirements, allowing for power-on-demand operation. Dynamic power management permits energy saving and lowers device operating temperatures, improving the reliability and lifetime of optoelectronic-devices such as vertical-cavity surface-emitting lasers (VCSELs). To implement dual-rate functionality, we include in the transmitter and receiver circuits separate high-speed and low-power data path modules. The high-speed module is designed for gigabit operation to achieve high bandwidth. A simpler low-power module is designed for megabit data transmission with low power consumption. The transceiver is fabricated in a 0.5 microm silicon-on-sapphire complementary metal-oxide semiconductor. The VCSEL and photodetector devices are attached to the transceiver's integrated circuit by flip-chip bonding. A free-space optical link system is constructed to demonstrate correct dual-rate functionality. Experimental results show reliable link operation at 2 Gbit/s and 100 Mbit/s data transfer rates with approximately 104 and approximately 9 mW power consumption, respectively. The transceiver's switching time between these two data rates is demonstrated as 10 micros, which is limited by on-chip register reconfiguration time. Improvement of this switching time can be obtained by use of dedicated input-output pads for dual-rate control signals.     

High-speed and high-sensitivity displacement measurement with phase-locked low-coherence interferometry

A novel high-speed and high-sensitivity displacement measurement sensing system, based on the phase-locked low-coherence interferometry, is presented. The sensing system is realized by comprising the Michelson fiber-optic interferometer. In order to obtain quadrature signals at the interferometer outputs, a 3×3 fused silica fiber-optic directional coupler is used. Therefore, the usage of the interferometer phase modulation as well as the usage of the lock-in amplification has been avoided. In this way, the speed of such a realized sensing system is significantly increased in comparison with the standard phase-locked interferometric systems that can be found elsewhere in the literature. The bandwidth of the realized sensing system is limited by the first resonance frequency of the used piezo actuator to 4.6 kHz. The estimated noise floor in the displacement measurement is approximately 180 pm/√Hz.     

256 × 256 Turnover-type free-space multichannel optical switch based on polarization control using liquid-crystal spatial light modulators

Free-space multichannel optical switches using polarization control are attracting interest for future telecommunication networks and interconnection networks in computers. We describe a switching architecture, the turnover type, for such free-space multichannel optical switches. The architecture makes it possible to realize a large-scale and transparent optical switch that is also compact. A 256 × 256 multichannel optical switch based on the architecture is designed and fabricated. To the authors' knowledge, the channel number of the fabricated switch is the largest yet reported among rearrangeable optical switches. Switching operation and signal transmission at 400 Mbits/s are performed successfully with a prototype switch.     

Discrete correlation processor as a building core of a digital optical computing system: architecture and optoelectronic embodiment

In this paper we present a general-purpose discrete correlation processor (DCP) expected to be the building core block of a digital optical computing system. The DCP-1 is embodied by optoelectronic devices such as a VCSEL and a complementary metal-oxide silicon photodetector. The application targets of the DCP-1 are optical interconnection and various types of digital optical computing. It is expected that digital optical computing techniques coupled with the optoelectronic technology will provide large capability and flexibility in information processing. Introduction of a processing scheme of optical array logic enlarges the applicable field of the DCP-1 as well as its processing capability. With the experimental DCP-1 a bit error rate smaller than 10(-9) was obtained for A . B? operation under a 500-kHz clock rate.     

All-optical quaternary logic gates

Conventional binary logic based operations restrict the speed of operations as well as information handling capacity. A way to overcome these limitations is the implementation of multivalued logic operations in the optical domain. Multivalued logic operations not only enhance the data handling capacities but also increase the speed of processing. integrating enormous potential bandwidth of optical fiber as information carrying medium and faster optoelectronic/optical switches with no hardware complexity. A new method is proposed for the implementation of all-optical quaternary inversion, MAX, MIN, and equality operations using frequency-encoded data. Cross phase modulation-based frequency conversion, polarization switch (PSW) characteristics of a semiconductor optical amplifier (SOA), frequency routing by a wave division multiplexer (MUX), and a demultiplexer (DMUX) have been exploited to implement the desired quaternary logic operations. Simulation results support the feasibility of the proposed scheme.     

High-speed electroabsorption modulation of composite-resonator vertical-cavity lasers

The high-speed characteristics of a composite-resonator vertical-cavity laser (CRVCL) under both smalland large-signal electroabsorption modulation are investigated. The maximum 23 dB modulation bandwidth of 12.5 GHz is measured. The theoretical modulation response of the CRVCL is derived from the standard rate equations, and the qualitative form is in agreement with the measured results. The CRVCL under electroabsorption modulation exhibits a promising potential to extend the modulation bandwidth beyond that of a conventional VCSEL. However, the CRVCL under large-signal electroabsorption modulation is limited to low data rates, and the large relaxation oscillation resonance must be suppressed for higher-speed digital? optical link applications.     

探地雷达收发开关系统的设计

 针对当前探地雷达中双天线存在严重耦合影响了信号检测的问题,开发了一种高速的开关系统.通过ADS电路仿真和参数优化,利用PIN管芯制作了一种串/并联结构的宽带高隔离度微带单刀双掷开关,设计了开关的电源电路和驱动电路.经过实验测量表明该开关系统达到了技术指标要求,能满足探地雷达的要求.     

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.     

Distortion analysis of bootstrap switch using volterra series

Linear behaviour of bootstrap switches is of critical importance in low-voltage analogue circuits and understanding the major factors affecting the linearity helps design a better switch. This study presents a theoretical approach for evaluating the distortion of bootstrap switches in the frequency domain based on the Volterra series. Five major factors affecting the linearity of the bootstrap switch are examined. In order to obtain a general design guideline the analysis is done in two parts. First, the distortion because of the nonlinear I?V characteristic of the main transistor of the switch is considered. In the second part, the distortion because of sampling errors, such as clock feed-through and charge injection, are added to the analysis. The theoretical results are verified by circuit simulations in a 0.18 μm CMOS process, using HSpice.