CLAP: a Crosstalk and Loss Analysis Platform for Optical Interconnects Special session on Silicon Photonics Interconnects: an Illusion or a Realistic Solution? Mahdi Nikdast1, Luan H. K. Duong1, Jiang Xu1, Sébastien Le Beux2, Xiaowen Wu1, Zhehui Wang1, Peng Yang1, and Yaoyao Ye1 1The Hong Kong University of Science and Technology 2Lyon Institute of Nanotechnology NOCS 2014, Ferrara, Italy Outline Introduction Crosstalk in basic optical elements Analytical models for the crosstalk and SNR CLAP: Crosstalk and Loss Analysis Platform Case study Summary 2014-10-17 HKUST 2 The road to Optical Interconnects Limitations of metallic interconnects in electronic NoCs: Parasitic resistance and capacitance High latency and power dissipation, and low bandwidth Consume kilowatts of power to achieve the communication bandwidth that will be required by multiprocessor systemson-chip (MPSoCs) by 2020 using the 14 nm process [Beausoleil, Proc. of IEEE’ 2008] ITRS* [ITRS (2000)] has pointed out the urgent need for new intra-chip interconnection technologies IBM ICON (Intra-Chip Optical Network) 3D-integated chip consists of several layers *International Technology Roadmap for Semiconductors 2014-10-17 HKUST 3 Optical Interconnects The Present and The Future 2014-10-17 HKUST 4 Optical Interconnects The Present and The Future Roadmap of Industrial photonics technologies (source: HP) 2014-10-17 HKUST 5 Why is Considering Crosstalk Noise Important? Crosstalk noise is an intrinsic characteristic of photonic devices widely used in optical NoCs Crosstalk noise is very small at the device level, and it has been ignored at the router and network levels! But, what if it cannot be ignored ? What is the impact of crosstalk noise on large scale ONoCs? What is the worst-case and the average Signal-to-Noise Ratio (SNR) in an ONoC? … 2014-10-17 HKUST 6 Crosstalk in Basic Optical Elements Inter-channel crosstalk Crosstalk signal is at a wavelength sufficiently different from the desired signal’s wavelength Intra-channel crosstalk Crosstalk signal is at the same wavelength as that of the desired signal or sufficiently close to it Cascading a wavelength demultiplexer (demux) with a wavelength multiplexer (mux), optical switches Can be coherent and incoherent Cannot be removed by filtering 2014-10-17 HKUST 7 Basic Optical Elements We consider first-order incoherent and coherent crosstalk 2014-10-17 HKUST 8 Basic Optical Elements II Optical modulator and photodetector models as a part of the E-O and O-E interfaces 2014-10-17 HKUST 9 Hierarchical Systematic Crosstalk Noise Analysis Network Level Router Level Device Level 2014-10-17 HKUST 10 Analytical Models for Crosstalk Let’s consider a parallel switching element as an example: [S. Xiao, Opt. Express’ 2007] 2014-10-17 HKUST Notation Definition Pin Input power Kp0 Crosstalk per MR (OFF) Lp0 Crosstalk per MR (ON) λMR MR’s resonant wavelength 11 Signal-to-Noise Ratio (SNR) in Optical Interconnects We have studied the SNR in optical interconnect architectures: Analysis of the worst-case and the average signal power, crosstalk noise power, and SNR Different optical interconnect architectures: mesh-based, folded-torus-based, fat-tree-based, and ring-based ONoCs using WDM Indicated the scalability constraints and power efficiency in different architectures Integrated the analytical models into a newly developed Crosstalk and Loss Analysis Platform (CLAP) 2014-10-17 HKUST 12 Crosstalk and Loss Analysis Platform (CLAP) 2014-10-17 HKUST 13 Some of CLAP’s Capabilities Analyzes the signal power, crosstalk noise power, and SNR in arbitrary ONoC architectures of any network size New version (v3.0) includes Coherent crosstalk analysis Optical router analyzer (higher orders of crosstalk) Provides the worst-case and the average results Available online with documentation: http://www.ece.ust.hk/~eexu 2014-10-17 HKUST 14 Case Study SUOR (Sectioned Un-directional Optical Ring) 2014-10-17 HKUST 15 Summary Studied the worst-case and the average crosstalk noise and SNR in optical interconnects Developed CLAP, an automated crosstalk and loss analysis platform that can analyze the signal power, crosstalk noise power, and SNR in different optical interconnect architectures Crosstalk noise is a critical issue, which restricts the scalability of optical interconnects and damages the SNR Different optical interconnect architectures have different SNR performances 2014-10-17 HKUST 16 Other Useful Tools and Resources An open tool for heterogeneous multiprocessor research and development: COSMIC: Heterogeneous Multiprocessor Benchmark Suite An open tool for networks-on-chip based on real applications: MCSL: Realistic Network-on-Chip Traffic Patterns An open tool for optical interconnect network research and development: OTemp: Optical Thermal Effect Modeling Platform We also maintain a bibliography on inter/intra-chip optical interconnect networks: Inter/Intra-Chip Optical Network Bibliography All are available: http://www.ece.ust.hk/~eexu 2014-10-17 HKUST 17 Acknowledgements Current group members Prof. Jiang Xu, Xiaowen Wu, Zhehui Wang, Xuan Wang, Zhe Wang, Luan Duong, and Peng Yang Past members Dr. Mahdi Nikdast, Dr. Yaoyao Ye, Dr. Weichen Liu, Prof. Sébastien Le Beux 2014-10-17 HKUST 18 Thanks! 2014-10-17 HKUST 19
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