662 research outputs found

    Quaternary pulse position modulation electronics for free-space laser communications

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    The development of a high data-rate communications electronic subsystem for future application in free-space, direct-detection laser communications is described. The dual channel subsystem uses quaternary pulse position modulation (QPPM) and operates at a throughput of 650 megabits per second. Transmitting functions described include source data multiplexing, channel data multiplexing, and QPPM symbol encoding. Implementation of a prototype version in discrete gallium arsenide logic, radiofrequency components, and microstrip circuitry is presented

    Single-Laser Multi-Terabit/s Systems

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    Optical communication systems carry the bulk of all data traffic worldwide. This book introduces multi-Terabit/s transmission systems and three key technologies for next generation networks. A software-defined multi-format transmitter, an optical comb source and an optical processing scheme for the fast Fourier transform for Tbit/s signals. Three world records demonstrate the potential: The first single laser 10 Tbit/s and 26 Tbit/s OFDM and the first 32.5 Tbit/s Nyquist WDM experiments

    Single-Laser Multi-Terabit/s Systems

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    Optical communication systems carry the bulk of all data traffic worldwide. This book introduces multi-Terabit/s transmission systems and three key technologies for next generation networks. A software-defined multi-format transmitter, an optical comb source and an optical processing scheme for the fast Fourier transform for Tbit/s signals. Three world records demonstrate the potential: The first single laser 10 Tbit/s and 26 Tbit/s OFDM and the first 32.5 Tbit/s Nyquist WDM experiments

    Optical packet networks : enabling innovative switching technologies

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    Les réseaux informatiques avec une grande capacité nécessitent des liaisons de transmission de données rapides et fiables pour prendre en charge les applications web en pleine croissance. Comme le nombre de serveurs interconnectés et la capacité de stockage des médias ne cessent daugmenter, les communications optiques et les technologies de routage sont devenues intéressantes grâce au taux binaire élevé et à lencombrement minimum offert par la fibre optique. Les réseaux optiques à commutation de paquets (OPSNs) offrent une flexibilité accrue dans la gestion de réseau. OPSNs exploitent les convertisseurs de longueur donde accordables (WC) pour minimiser la probabilité de blocage et fournir une allocation dynamique des longueurs donde. Les émetteurs optiques basés sur des sources multi-longueurs donde se présentent comme une solution intéressante en termes de coût, dencombrement et defficacité énergétique par rapport aux autres types de lasers. Les convertisseurs de longueurs donde doivent permettre des taux binaires élevés et une transparence à une grande variété de formats de modulation, tout en offrant une réponse rapide, des niveaux de puissance modérés et un rapport de signal à bruit optique (OSNR) acceptable à la sortie. Plusieurs technologies de conversion de longueur donde ont été proposées dans la littérature. Lutilisation du mélange à quatre ondes (FWM) dans les amplificateurs optiques à semi-conducteurs (SOA) permet lutilisation de faibles niveaux de puissance dentrée et offre une bonne efficacité de conversion ainsi que la possibilité dintégration photonique. Les SOAs offrent donc un excellent compromis par rapport aux autres solutions. Pour couvrir une plus large bande de conversion, nous utilisons le schéma exploitant le FWM avec doubles pompes dans les SOAs. Pour la stabilité de phase, les pompes viennent d’un laser en mode bloqué (QDMLL) qui sert comme source multi-longueurs donde. Deux modes du QDMLL sont sélectionnés par un filtrage accordable et servent comme doubles pompes. Un filtre accordable placé à la sortie du SOA sert à sélectionner le produit du FWM pour le signal final. Nous étudions le convertisseur de longueur donde proposé et comparons sa performance pour différents formats de modulation (modulation dintensité et de phase) et à différents débits binaires (10 et 40 Gbit/s). Le taux derreur binaire, lefficacité de conversion et la mesure de lOSNR sont présentés. Nous démontrons aussi la possibilité de simultanément convertir en longueurs donde les données et l’étiquette. Les données à haut débit et l’étiquette à faible débit se retrouvent dans une seule bande de longueurs d’onde, et ils sont convertis ensemble avec une bonne efficacité. Notre démonstration se concentre sur les performances de conversion, donc les données et létiquette sont des signaux continus plutôt que de paquets optiques. Des mesures de taux derreur binaire ont été effectuées à la fois pour les données et pour létiquette. Nous proposons aussi lutilisation de QDMLL comme source de transmetteurs WDM pour deux applications différentes: unicast et multicast. Nous démontrons aussi sa compatibilité avec le format de transmission DQPSK à haut débit binaire. Nous évaluons la performance du DQPSK en terme de taux derreur binaire et comparons sa performance à celle dune source laser à cavité externe.Large scale computer networks require fast and reliable data links in order to support growing web applications. As the number of interconnected servers and storage media increases, optical communications and routing technologies become interesting because of the high speed and small footprint of optical fiber links. Furthermore, optical packet switched networks (OPSN) provide increased flexibility in network management. Future networks are envisaged to be wavelength dependent routing, therefore OPSN will exploit tunable wavelength converters (WC) to enable contention resolution, reduce wavelength blocking in wavelength routing and switching, and provide dynamic wavelength assignment. Optical transmitters based on multi-wavelength sources are presented as an attrative solution compared to a set of single distributed feedback lasers in terms of cost, footprint and power consumption. Wavelength converters should support high bit rates and a variety of signal formats, have fast setup time, moderate input power levels and high optical signal-to-noise ratio at the output. Several wavelength conversion technologies have been demonstrated. The use of four wave mixing (FWM) in semiconductor optical amplifiers (SOAs) provides low input power levels, acceptable conversion efficiency and the possibility of photonic integration. SOAs therefore offer excellent trade-offs compared to other solutions. To achieve wide wavelength coverage and integrability, we use a dual pump scheme exploiting four-wave mixing in semiconductor optical amplifiers. For phase stability, we use a quantum-dash mode-locked laser (QD-MLL) as a multi-wavelength source for the dual pumps, with tunability provided by the frequency selective filter. We investigate the proposed wavelength converter and compare its performance of wavelength conversion for different non-return-to-zero (NRZ) intensity and phase modulation formats at different bit rates (10 and 40 Gbit/s). Bit error rate, conversion efficiency and optical signal-to-noise ratio measurements are reported. We demonstrate the possibility of tightly packed payload and label wavelength conversion at very high data baud rate over wide tuning range with good conversion efficiency. Our demonstration concentrates on conversion performance, hence continuous payload and label signals were used without gating into packets. Bit error measurements for both payload and label were performed. We propose the use of QD-MLL as multi-wavelength source for WDM unicast and multicast applications and we investigated its compatibility with DQPSK transmission at high bit rate. We quantify DQPSK performance via bit error rate measurements and compare performance to that of an external cavity laser (ECL) source

    Ultra-High-Speed Optical Serial-to-Parallel Data Conversion in a Silicon Nanowire

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    We demonstrate conversion from 64×10 Gbit/s OTDM to 25 GHz DWDM by time-domain optical Fourier transformation. Using a single silicon nanowire, 40 of 64 OTDM tributaries are simultaneously converted to DWDM channels within FEC limits.</p

    Optical packet switching using multi-wavelength labels

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    OTDM Networking for Short Range High-Capacity Highly Dynamic Networks

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    PAM4-바이너리 브리지 칩용 PAM4 트랜스미터 설계

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    학위논문(석사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 정덕균.고성능 컴퓨팅 시스템, 대용량의 데이터 센터, AI 기술의 발전으로 인해 유선 통신의 대역폭 요구 수준은 기하급수적으로 증가하고 있다. 그러나 I/O 회로의 핀당 대역폭의 향상은 통신 채널의 다양한 한계로 인해 어려움을 겪고 있다. 이는 차세대 DRAM 분야에서도 예외는 아니다. 핀당 데이터 전송 속도를 증가시키는 연구 방향에서는 어느 정도 한계에 봉착하면서 최근에는 High Bandwidth Memory (HBM)와 같이 핀의 개수를 급격히 늘려서 대역폭을 증가시키는 기술도 발전하고 있다. 다른 접근 방식 중 한가지가 다중 레벨 신호 방식이다. 기존의 Non-Return-to-Zero (NRZ) 신호 대신에 다중 레벨 신호 방식을 이용하면 동일한 Nyquist 주파수에서 데이터 속도를 높일 수 있고 이는 DRAM의 차세대 고대역폭 I/O 인터페이스에 좋은 솔루션이 될 수 있으며 현재까지는 4레벨 펄스 진폭 변조 방식 (PAM-4)이 널리 채택되어 있다. 하지만 현재 PAM-4 방식 DRAM이 양산 단계가 아니기 때문에 PAM-4 전용 Memory Tester가 없는 상황이다. 본 논문에서는 차세대 메모리 테스트를 위한 32 Gb/s PAM4 바이너리 브리지에서의 트랜스미터를 제안한다. NRZ 테스터에서 브리지로 전송된 저속 데이터는 고속 PAM4 데이터로 변환되어 메모리로 전달된다. 접지 종단 PAM4 드라이버는 2-탭 피드포워드 이퀄라이저로 출력 전류를 제어하여 0.95의 레벨 불일치 비율 (RLM)을 달성함으로써 단일 종단 출력을 제공한다. 40 nm CMOS 기술로 제작된 브리지 트랜스미터는 0.57 mm2의 활성 영역을 차지하고 102.1 mW의 전력을 소모한다.With the advancement of high-performance computing systems, large-capacity data centers, and AI technologies, the level of bandwidth demand for wired communication is increasing exponentially. However, the improvement of the bandwidth per pin in the I/O circuit compared to the required bandwidth level is difficult due to various limitations of the transmission channel. This is no exception in the next generation of DRAM. While facing limitations from the perspective of research that increases data transmission speed per pin, technologies that increase I/O bandwidth by rapidly increasing the number of pins, such as High Bandwidth Memory (HBM), have also recently developed. One of the other approaches is a multi-level signaling method. Using a multi-level signaling method instead of a conventional Non-Return-to-Zero (NRZ) signal can increase data speed at the same Nyquist frequency, which can be a good solution for the next-generation high-bandwidth I/O interface of DRAM, and so far, a four-level Pulse Amplitude Modulation (PAM-4) has been widely adopted. However, since PAM4 DRAM is not in the mass production stage yet, there is no memory tester dedicated to PAM4 signaling. This paper proposes a transmitter block on a 32 Gb/s PAM4 binary bridge for next-generation memory testing. The low-speed data transmitted from the NRZ tester to the bridge is converted into high-speed PAM4 data through half-rate clock control and transferred to the memory. The ground termination PAM4 driver provides a single-ended output by controlling the output current with a two-tap feed forward equalizer to achieve a Level separation Mismatch Ratio (RLM) of 0.95. Bridge transmitter manufactured with 40 nm CMOS technology occupies an active area of 0.57 mm2 and consumes 102.1 mW of power.ABSTRACT I CONTENTS Ⅲ LIST OF FIGURES Ⅴ LIST OF TABLES Ⅶ CHAPTER 1 INTRODUCTION 1 1.1 MOTIVATION 1 1.2 THESIS ORGANIZATION 4 CHAPTER 2 BACKGROUNDS 5 2.1 OVERVIEW 5 2.2 BASIC OF MULTI LEVEL SIGNALING 7 2.3 NECESSITY OF PAM4-BINARY BRIDGE 11 CHAPTER 3 DESIGN OF PAM4 TRANSMITTER FOR PAM4-BINARY BRIDGE 14 3.1 DESIGN CONSIDERATION 14 3.2 OVERALL ARCHITECTURE 17 3.3 CIRCUIT IMPLEMENTATION 19 3.3.1 CLOCK GENERATOR 19 3.3.2 PARALLEL PRBS GENERATOR 23 3.3.3 DATA ALIGN / GRAY CODE ENDCODER 26 3.3.4 FFE CONTROL/ SERIALIZER 30 3.3.5 PAM4 DRIVER 33 CHAPTER 4 MEASUREMENT RESULTS 38 4.1 CHIP PHOTOMICROGRAPH 38 4.2 MEASUREMENT SETUP 39 4.3 MEASUREMENT RESULTS 40 4.4 PERFORMANCE SUMMARY 42 CHAPTER 5 CONCLUSION 46 BIBLIOGRAPHY 47 초 록 50석
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