With the rapid growth in intra-datacenter traffic, the high power consumption stemming from the huge number of electrical switches is becoming a critical issue. Hence, high-port-count optical circuit switches are urgently needed. In this paper, we overview recently developed optical circuit switch architecture based on two-dimensional switches, i.e., space switches and wavelength-routing switches. The attainable maximum switch port counts and hardware requirements are quantitatively evaluated through extensive computer simulations that consider 10-Gbps intensity modulation with direct detection systems, 43-Gbps differential quadrature phase-shift keying with self-coherent detection systems, and 128-Gbps dual-polarization quadrature phase-shift keying with coherent detection systems. The simulation results confirm the existence of switching architecture that can accommodate more than 1,000 ports with relatively light hardware requirements.

Design and Evaluation of Optical Circuit Switches for Intra-Datacenter Networking

We review technologies and architectures for WDM optical IP networks from the viewpoint of capital expenditure and network energy consumption. We show how requirements of low cost and low energy consumption can influence the choice of switching technologies as well as the overall network architecture.

Evolution of WDM Optical IP Networks : A Cost and Energy Perspective

We investigate a large-scale and fast optical circuit switch system that uses digital coherent technologies. The achievable port count is expanded by introducing colorless detection which eliminates channel selecting filters at receivers. Wavelength selection is performed using a shared local oscillator (LO) bank, which is configured by combining a multi-wavelength optical source with Silicon-photonic tunable filters (TFs). Microsecond switching times are realized with the thermo-optic effect available with the Silicon-photonic TF. Design optimization of the proposed system handles complex level of freedom, i.e., available wavelength number, space switch port count, optical amplifier location and gain, and device loss. In addition, colorless coherent detection induces penalties, which further complicates switch scale assessment. In this paper, we develop a simulator to clarify how those parameters affect switch performance; the switch throughput is maximized with consideration of the degradation stemming from colorless detection. The design performance accurately matches results measured in various system scenarios. A dual-carrier 256-Gb/s DP-QPSK experiment successfully demonstrates a 1,856 $ \times $ 1,856 optical switch system with switching time under 3.52 μs. The resulting total throughput is 441 Tb/s assuming 7%-overhead HD-FEC. To the best of our knowledge, this is the first demonstration of 400-Tbps class large bandwidth optical switches that use TFs as wavelength selective devices for coherent detection.

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Scalable and Fast Optical Circuit Switch Based on Colorless Coherent Detection: Design Principle and Experimental Demonstration

Space division multiplexing (SDM), as a potential means of enhancing the capacity of optical transmission systems, has attracted widespread attention. However, the adoption of SDM technology has also additionally increased resource dimensions, introduced complex crosstalk, and made it difficult to integrate multi-dimensional fragments. These factors force the transmission constraints to be more complicated. Especially, some factors have a mutual restraint relationship, and excessive consideration of certain factors will cause the deterioration of other ones. Therefore, how to comprehensively consider the associated factors to achieve trade-offs and improve network performance is a problem worthy of study. This paper exploits the advantages of self-organizing feature mapping (SOFM) model to process multi-dimensional data with relevant features. Firstly, multiple constraints will be input into SOFM as mode vectors from the core level. Then, by judging the similarity between the competition layer neuron and the pattern vector, the position of the winning neuron is located, which determines the transmission level of each core. Finally, a routing, core, and spectrum allocation scheme is proposed by preferentially locating the core with higher transmission quality. Along the selected core, the available slots will be classified twice respectively by the number of adjacent cores and crosstalk direction to quickly find the spectrum blocks with relatively small crosstalk. Results indicate the scheme can reduce blocking probability and the resource fragmentation. Further, it can increase the resource utilization within tested network load. 

Multi-Associated Parameters Aggregation-Based Routing and Resources Allocation in Multi-Core Elastic Optical Networks

We analyze the cost of networks consisting of optical cross-connect nodes with different architectures for realizing the next generation large bandwidth networks. The node architectures include wavelength granular and fiber granular optical routing cross-connects. The network cost, capital expenditure (CapEx), involves link cost and node cost, both of which are evaluated for different scale networks under various traffic volumes. Numerical experiments demonstrate that the subsystem modular architecture with wavelength granular routing yields the highest cost effectiveness over a wide range of parameter values. key words: ROADM, OXC, fiber cross-connect, routing and wavelength assignment

Assessment of Optical Node Architectures for Building Next Generation Large Bandwidth Networks

We present a large-scale optical circuit switch architecture using wavelength-tunable and bandwidth-variable silicon photonic filters. The attainable switch port count is quantitatively evaluated through extensive computer simulations. The requirements for constructing a 1, $024\times1$ ,024 optical circuit switch are analyzed on 10-, 28-, and 56-Gb/s signals. The simulation results are verified through transmission experiments.

A Large-Scale Optical Circuit Switch Using Fast Wavelength-Tunable and Bandwidth-Variable Filters

This paper analyzes different optical cross-connect node architectures in terms of capital expenditure (CapEx) of networks. Numerical experiments demonstrate that the subsystem modular architecture yields the highest cost effectiveness over a wide range of traffic.

Assessment of optical cross-connect architectures for the creation of next generation optical networks

We demonstrate fast optical circuit switching from a monolithically integrated optical space switch and wavelength-tuneable filter on a silicon-photonic chip. Feasibility is confirmed by proof-of-concept experiments using 43-Gbps DQPSK signals. Switching time of $10\ \mu \text{s}$ is attained.

Mungun-Erdene Ganbold

Papers

Design and Evaluation of Optical Circuit Switches for Intra-Datacenter Networking

A Large-Scale Optical Circuit Switch Using Fast Wavelength-Tunable and Bandwidth-Variable Filters

Assessment of Optical Node Architectures for Building Next Generation Large Bandwidth Networks

Assessment of optical cross-connect architectures for the creation of next generation optical networks

Fast Optical Circuit Switch Using Monolithically Integrated Silicon-Photonic Space Switch and Wavelength-Tuneable Filter