Board-level optical interconnection and signal distribution using embedded thin-film optoelectronic devices

Optical interconnection and signal distribution at the backplane, board, and substrate level can be implemented using thin-film active optoelectronic devices embedded in polymer waveguide structures. These active embedded devices eliminate the need for optical beam turning to and from photodetectors and emitters, respectively, for inputs and outputs to the substrate waveguides. In this paper, optical interconnections using fully embedded thin-film metal-semiconductor-metal (MSM) photodetectors in polymer optical waveguides are demonstrated, and the experimental characterization of these thin-film MSMs embedded in polymer waveguides is reported. To illustrate the potential for high-level signal distribution at the backplane, board, and substrate levels, a 1/spl times/4 balanced multimode interference (MMI) coupler has also been demonstrated in a photoimageable polymer for the first time. Finally, a 1/spl times/4 thin-film MSM photodetector array has been embedded in the output arms of the a photoimageable polymer MMI for the first time, and the MSM array photocurrent outputs from the 4 arms show that highly balanced optical signal distribution has been achieved.     

SMT-compatible large-tolerance "OptoBump" interface for interchip optical interconnections

A new optical interface called OptoBump has been developed to couple optoelectronic packages to an optoelectronic printed circuit board, thus enabling economical chip-to-chip optical interconnections. The optoelectronic packages have vertical-cavity surface-emitting laser (VCSEL) and PD-array chips in their cavity and an large scale integrated (LSI) mounted on top. A package converts high-speed electrical signals from the LSI into an array of optical signals, which are emitted from the bottom. The PCB contains integrated polymer optical waveguides to optically connect packages, and the use of surface-mount technology (SMT) to mount packages on the printed circuit board (PCB) keeps assembly costs low. The key to making the OptoBump interface fully compatible with SMT is the integration of microlens arrays directly into both packages and the PCB. A wide, collimated optical beam couples a package to the board across a narrow air gap and provides a large tolerance to misalignment during the SMT process. This paper explains the concept of the OptoBump interface, the optical coupling design by ray-trace simulation, and the fabrication of polymer microlenses and polymer waveguides. Experimental results revealed that the OptoBump interface provides a large tolerance of /spl plusmn/50 /spl mu/m, which is large enough for use with SMT. The OptoBump interface can replace high-speed electrical wiring at the chip level and also offers the benefit of not having any optical fibers or connectors on the board. Thus, it has the potential to bring about a revolutionary change in optoelectronic packaging.     

Integrated optical interconnections

The use of optical interconnections between processors, boards, chips, and gates in electronic digital systems to overcome the current performance limitations is described. The advantages of optical interconnections in relation to the interconnection distance, the data capacity, and the interconnection functions are presented. The devices which will support practical implementation of optical interconnections and the integration of optical interconnection devices are discussed. The development of future integrated optoelectronic materials, processing, and fabrication technologies to support integrated optical electronics is also discussed     

Microwave photonic multichip modules

The increasing use of microwave frequencies and gigabit per second transmission rates in optical-fibre systems and the corresponding interest in using optical techniques for microwave systems are spurring the development of microwave photonic circuits. Despite a considerable investment in research and development, monolithic photonic and optoelectronic integrated circuits have not entered into widespread production. The paper illustrates that for the majority of microwave photonic applications, the multichip module approach is better suited in terms not only of performance but also of economy and of ease of manufacture. The advantages of the silicon optical bench for optoelectronic integration are discussed in depth. It is then shown how, with suitable modifications, silicon-based multichip modules can also provide interconnections to microwave devices, thus creating microwave photonic multichip modules     

二氧化硅平面光波导器件的研究进展

二氧化硅平面光波导(PLC)器件以其低损耗、高工艺容差,以及与CMOS工艺兼容和与单模光纤模场匹配良好等优点,在光通信、光互连和集成光学中得到了广泛的应用.文章综述了二氧化硅平面光波导器件及其应用的进展,重点针对分束器、阵列波导光栅、可调光衰减器及其集成器件的最新研究进行了介绍,对未来发展趋势进行了展望.     

GaAs/GaAlAs selective MOCVD epitaxy and planar ion-implantation technique for complex integrated optoelectronic circuit applications

We report on a monolithic integration technique incorporating selective GaAs/GaAlAs optical device epitaxy (based on metalorganic chemical vapor deposition (MOCVD)) and planar ion-implanted GaAs devices, formulated for application to complex integrated optoelectronic circuits. This integration scheme offers fabrication compatibility of epitaxially grown optoelectronic devices with maturing GaAs electronic circuit approaches which require selective multiple implants and small gate geometries. Details of the monolithic integration technique and an example of its application to an optoelectronic transmitter are described.     

A three-dimensional high-throughput architecture usingthrough-wafer optical interconnect

This paper presents a three-dimensional, highly parallel, optically interconnected system to process high-throughput stream data such as images. The vertical optical interconnections are realized using. Integrated optoelectronic devices operating at wavelengths to which silicon is transparent. These through-wafer optical signals are used to vertically optically interconnect stacked silicon circuits. The thin film optoelectronic devices are bonded directly to the stacked layers of silicon circuitry to realize self-contained vertical optical interconnections. Each integrated circuit layer contains analog interface circuitry, namely, detector amplifier and emitter driver circuitry, and digital circuitry for the network and/or processor, all of which are fabricated using a standard silicon integrated circuit foundry. These silicon circuits are post processed to integrate the thin film optoelectronics using standard, low cost, high yield microfabrication techniques. The three-dimensionally integrated architectures described herein are a network and a processor. The network has been designed to meet off-chip I/O using a new offset cube topology coupled with naming and renting schemes. The performance of this network is comparable to that of a three-dimensional mesh. The processing architecture has been defined to minimize overhead for basic parallel operations. The system goal for this research is to develop an integrated processing node for high-throughput, low-memory applications     

Fully Embedded Board-Level Optical Interconnects From Waveguide Fabrication to Device Integration

This paper presents the latest progress toward fully embedded board-level optical interconnects in the aspect of waveguide fabrication and device integration. A one-step pattern transfer method is used to form a large cross-section multimode waveguide array with 45deg micromirrors by silicon hard molding method. Optimized by a novel spin-coating surface smoothing method for the master mold, the waveguide propagation loss is reduced to 0.09 dB/cm. The coupling efficiency of the metal-coated reflecting mirror, which is embedded in the thin-film waveguide, is simulated by an M² factor revised Gaussian beam method and is experimentally measured to be 85%. The active optoelectronic devices, vertical surface emitter lasers and p-i-n photodiodes, are integrated with the mirror-ended waveguide array and successfully demonstrate a 10 Gbps signal transmission over the embeddable optical layer.     

Fabrication and characterization of polymer optical waveguides with integrated micromirrors for three-dimensional board-level optical interconnects

This paper describes the fabrication and characterization of optical/electrical printed circuit boards (O/E-PCB) with embedded multimodal step index (MM-SI) waveguides and integrated out-of-plane micromirrors (IMMs) for three-dimensional (3-D) optical interconnects. Optical circuitry is built up on PCBs using UV lithography; 45/spl deg/ input/output (I/O) couplers are fabricated by inclined exposure. Commercial polymers are used as optical core and cladding materials. Critical mirror properties of angle, surface quality, reflectivity, and coupling efficiency are characterized experimentally and theoretically. Optical and scanning electron microscopy, white light interferometry, and fiber scanning method are used in the investigations. Sloping profiles measured as a function of the incident light showed the attainment of mirror angles of /spl alpha/=36/spl deg/-45/spl deg/ with /spl plusmn/2/spl deg/ consistency. Near-field optical imaging with a white light source showed that out-of-plane beam turning was achieved. Topography investigations revealed a rectilinear negative tapering shape regardless of the incoming beam angle or type of substrate. However, higher substrate reflectancy was observed to lower the mirror angle. The average propagation loss measured for 10-cm-long waveguides at /spl lambda/=850 nm by the cut-back method was 0.60 dB/cm; the excess loss calculated for the mirror coupling was 1.8-2.3 dB. The results showed that the IMMs can be incorporated in O/E-PCBs to couple light in and out of planar waveguides. Furthermore, the presented results indicate that optical waveguides with integrated micromirrors for optical 3-D wiring can be produced compatible with volume manufacturing techniques.     

Realistic end-to-end simulation of the optoelectronic links andcomparison with the electrical interconnections for system-on-chipapplications

A detailed comparison of optoelectronic versus electrical interconnections for system-on-chip applications is performed in terms of signal latency and power consumption. Realistic end-to-end models of both interconnection schemes are employed in order to evaluate critical performance parameters. A variety of electrical and optoelectronic interconnection configurations are implemented and simulated using accurate optical device and electronic circuit models integrated under an integrated circuit (IC) design computer-aided design tool. Two commercial complementary metal-oxide-semiconductor (CMOS) technologies (0.8 μm and 0.25 μm) are used for the estimation of the signal latency and the power consumption as a function of the interconnection length for the different link configurations. It was found that optoelectronic interconnects outperform their electrical counterparts, under certain conditions, especially for relatively long lines and multichannel data links     

Self-Written Waveguide Optical Pin Fabricated Using Photomask Transfer Method

This letter reports on a new self-written waveguide (SWW) optical interconnection pin. The SWW-pin is formed directly on an optical device using a photomask transfer method and has a 45$^circ$mirror on the end-face. The processed end-face provides 90$^circ$optical path redirection and enables strict handling and alignment in optical interconnections on an optoelectronic printed-wiring board. We present 90$^circ$path redirection characteristics of an SWW-pin having a coupling loss of 1.1 dB.     

Rationale and challenges for optical interconnects to electronicchips

The various arguments for introducing optical interconnections to silicon CMOS chips are summarized, and the challenges for optical, optoelectronic, and integration technologies are discussed. Optics could solve many physical problems of interconnects, including precise clock distribution, system synchronization (allowing larger synchronous zones, both on-chip and between chips), bandwidth and density of long interconnections, and reduction of power dissipation. Optics may relieve a broad range of design problems, such as crosstalk, voltage isolation, wave reflection, impedence matching, and pin inductance. It may allow continued scaling of existing architectures and enable novel highly interconnected or high-bandwidth architectures. No physical breakthrough is required to implement dense optical interconnects to silicon chips, though substantial technological work remains. Cost is a significant barrier to practical introduction, though revolutionary approaches exist that might achieve economies of scale. An Appendix analyzes scaling of on-chop global electrical interconnects, including line inductance and the skin effect, both of which impose significant additional constraints on future interconnects     

A V-Band Beam-Steering Antenna on a Thin-Film Substrate With a Flip-Chip Interconnection

We propose a planar V-band beam-steering antenna based on a millimeter-wave (mm-wave) system-on-package technology using advanced thin-film technology on a silicon mother board. The thin-film substrate has the capability of integrated passive elements and flip-chip interconnection. Space-consuming components such as a microstrip Rotman lens and patch antennas are implemented on a low-loss, low-cost, and low-dielectric-constant material, benzocyclobutane. V-band monolithic microwave integrated circuits, a power amplifier, and a SP4T switch, are flip-chipped on the thin-film substrate while minimizing parasitic effects. The fabricated antenna module shows if-plane beam steering at four angles, plusmn6deg and plusmn20deg. The measured effective isotropic radiated power is in the range of 17.3-18 dBm. To our knowledge, this is the first demonstration of a planar mm-wave beam-steering antenna module on a thin-film substrate incorporating integrated terminating loads and flip-chip interconnections.     

半导体光集成电路

半导体光集成电路(PIC)是光电子集成电路(OEIC)的一个分支,它侧重于光学互连的导波光电子器件的单片集成。由于Ⅲ-Ⅴ族材料外延晶体生长和相关工艺技术方面的进步,这一研究领域最近取得明显进展。本文讨论了集成有源和无源光波导的某些必要技术,并介绍了几种典型器件。     

Planar packaging of free-space optical interconnections

Planar optics is an approach to build integrated free-space optical systems on single substrates. Computer-aided design, lithographic fabrication, and micro-bonding techniques are used to package the optics in a compact way. This paper reviews recent work on planar optics. It discusses various aspects of the fabrication, the design, and the application of planar optics as an interconnection technology for optoelectronic computing and switching systems     

Radio-Optical Dual-Mode Communication Modules Integrated With Planar Antennas

This paper presents new results on integrated devices for radio and free-space optical dual-mode communication. Two novel hybrid packaging schemes using two different microwave printed antenna designs are presented for the integration of radio-optical front-end circuits on a planar compact printed circuit board with shared electrical and structural components. Full-wave electromagnetic (EM) simulations are presented for antenna optimization to minimize EM interference between the radio and optical circuits. A hybrid radio-optical package design is developed, prototyped, and experimentally studied using a modified quasi-Yagi antenna with split directors to form pads for opto-electronic device integration. Dual-mode link connectivity is investigated in simulations and experiments. A data rate of 2.5 Gb/s is demonstrated for the optical channel despite 15–20-dB signal coupling between the optical and microwave circuits.      

Tolerance Analysis for Multilayer Optical Interconnections Integrated on a Printed Circuit Board

Polymer multilayer optical interconnections have gained interest over the past few years in view of their ability to increase the integration density, increase the routing flexibility, and make full use of the characteristics of 2D optoelectronic elements. The alignment between the functional elements in the different optical layers has to be sufficiently accurate in ensuring a high overall efficiency of the system. Numerical simulations have been used as a tool to determine whether laser ablation can be used as an alternative technology for the structuring of the functional elements of optical interconnections into a polymer optical layer. The experimentally achievable alignment accuracies are compared to tolerance ranges for an excess loss les 1 dB obtained from the numerical study. The experimental achievements show that the alignment accuracies fall within the numerical tolerance ranges and have a good reproducibility. Experimental realizations of a two-layer multimode waveguide and inter- and out-of-plane- coupling structures are discussed and shown.     

Optical interconnections for parallel and distributed computing

This paper reports the application of optical interconnections to a parallel an distributed computing system in the form of a calibration-free 64-Gbps/board parallel optical interconnection sub-system mounted directly on the four-CPU processor board of a newly developed parallel-processing machine, “RWC-1”. The sub-system is composed of eight parallel optical module/single-chip link large-scale integrated circuit pairs. The subsystem successfully transmitted parallel data for a variety of link lengths (between 1 m and 1 km), and with deskewing and synchronizing functions, phase-matching calibration for link lengths is automatic. Further, a method is described for the simplified merging of optical interconnections into electronic systems     

基于Pspice光发射机驱动电路的仿真分析

根据发光二极管（LED）和双异质结激光器（DH-LD）的Pspice等效子电路程序,将它们做成新的元件嵌入Pspice A/D 8.0电路仿真平台中。利用该平台对各种光发射机的光驱动回路进行模拟,证明用光电子器件的等效电路模型来模拟光电集成回路的可行性和便利性。