The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Daoxin Dai - One of the best experts on this subject based on the ideXlab platform.
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Multimode silicon photonics integrated devices
2016 IEEE International Nanoelectronics Conference (INEC), 2016Co-Authors: Daoxin DaiAbstract:Mode-division-multiplexing (MDM) technology has attracted much attention because of the potential to enhance the capacity of an optical-Interconnect Link for a single wavelength carrier. In this case, one should consider not only the fundamental mode but also the higher-order modes for the design of photonic integrated devices, and thus some novel devices are required. As silicon photonics has become very popular because of their CMOS compatibility, it is interesting to develop some multimode photonic integrated devices on silicon. This paper gives a review on multimode silicon photonics.
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Silicon nanophotonic integrated devices enabling multiplexed on-chip optical Interconnects
Integrated Optics: Physics and Simulations II, 2015Co-Authors: Daoxin Dai, Jian Wang, Sitao ChenAbstract:Advanced multiplexing technologies including wavelength-division-multiplexing (WDM), polarization-division multiplexing (PDM), and mode-division multiplexing (MDM) have been utilized as a cost-effective solution to enhance the capacity of an optical-Interconnect Link. The on-chip (de)multiplexers, including WDM filters, PDM devices, and MDM devices, are the most important key components in a multi-channel multiplexed optical Interconnect system. Hybrid (de)multiplexer to enable various multiplexing technologies simultaneously are becoming more and more important to achieve many channels. In this paper we give a review for our recent work on silicon photonic integrated devices for realizing multi-channel multiplexed on-chip optical Interconnects.
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silicon hybrid demultiplexer with 64 channels for wavelength mode division multiplexed on chip optical Interconnects
Optics Letters, 2014Co-Authors: Jian Wang, Sitao Chen, Daoxin DaiAbstract:A monolithically integrated 64-channel hybrid demultiplexer on silicon is demonstrated experimentally to enable wavelength-division-multiplexing and mode-division-multiplexing simultaneously for realizing an ultra-large capacity optical-Interconnect Link. The present hybrid demultiplexer consists of a four-channel mode multiplexer realized with three cascaded asymmetrical directional-couplers and four identical arrayed-waveguide gratings (AWGs) with 16 channels. For the fabricated hybrid multiplexer, the excess loss and the crosstalk are about −7 and −10 dB, respectively. Better performances can be achieved by minimizing the imperfections (particularly in AWGs) in the fabrication processes. The present hybrid demultiplexer is scalable to have more channels by utilizing more wavelengths, modes, and polarizations.
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Silicon hybrid demultiplexer with 64 channels for wavelength/mode-division multiplexed on-chip optical Interconnects.
Optics letters, 2014Co-Authors: Jian Wang, Sitao Chen, Daoxin DaiAbstract:A monolithically integrated 64-channel hybrid demultiplexer on silicon is demonstrated experimentally to enable wavelength-division-multiplexing and mode-division-multiplexing simultaneously for realizing an ultra-large capacity optical-Interconnect Link. The present hybrid demultiplexer consists of a four-channel mode multiplexer realized with three cascaded asymmetrical directional-couplers and four identical arrayed-waveguide gratings (AWGs) with 16 channels. For the fabricated hybrid multiplexer, the excess loss and the crosstalk are about −7 and −10 dB, respectively. Better performances can be achieved by minimizing the imperfections (particularly in AWGs) in the fabrication processes. The present hybrid demultiplexer is scalable to have more channels by utilizing more wavelengths, modes, and polarizations.
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Configuration of an Optical Transmitter Enabling Wavelength- and Mode-Division Multiplexed On-Chip Optical-Interconnects
Asia Communications and Photonics Conference 2014, 2014Co-Authors: Daoxin DaiAbstract:Configuration of an optical transmitter for realizing a two-dimensional hybrid multiplexing technology is proposed to enable the wavelength-division-multiplexing and mode-division-multiplexing technologies simultaneously. The capacity of an on-chip optical Interconnect Link can be enhanced by N×M times when N wavelengths as well as M mode-channels for each wavelength are involved.
Jian Wang - One of the best experts on this subject based on the ideXlab platform.
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Demonstration of on-Chip Hybrid (de)Multiplexer with 4×32 Channels for Simultaneous Mode- and Wavelength-Division Multiplexing
Conference on Lasers and Electro-Optics, 2020Co-Authors: Xiaoping Cao, Shuang Zheng, Feng Cui, Jian WangAbstract:We demonstrate on-chip monolithically integrated hybrid (de)multiplexer with 4×32 channels for simultaneous mode- and wavelength-division multiplexing for ultra-large capacity optical Interconnect Link. The chip consists of 4-channel mode (de)multiplexer and 32-channel arrayed waveguide grating.
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Silicon nanophotonic integrated devices enabling multiplexed on-chip optical Interconnects
Integrated Optics: Physics and Simulations II, 2015Co-Authors: Daoxin Dai, Jian Wang, Sitao ChenAbstract:Advanced multiplexing technologies including wavelength-division-multiplexing (WDM), polarization-division multiplexing (PDM), and mode-division multiplexing (MDM) have been utilized as a cost-effective solution to enhance the capacity of an optical-Interconnect Link. The on-chip (de)multiplexers, including WDM filters, PDM devices, and MDM devices, are the most important key components in a multi-channel multiplexed optical Interconnect system. Hybrid (de)multiplexer to enable various multiplexing technologies simultaneously are becoming more and more important to achieve many channels. In this paper we give a review for our recent work on silicon photonic integrated devices for realizing multi-channel multiplexed on-chip optical Interconnects.
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silicon hybrid demultiplexer with 64 channels for wavelength mode division multiplexed on chip optical Interconnects
Optics Letters, 2014Co-Authors: Jian Wang, Sitao Chen, Daoxin DaiAbstract:A monolithically integrated 64-channel hybrid demultiplexer on silicon is demonstrated experimentally to enable wavelength-division-multiplexing and mode-division-multiplexing simultaneously for realizing an ultra-large capacity optical-Interconnect Link. The present hybrid demultiplexer consists of a four-channel mode multiplexer realized with three cascaded asymmetrical directional-couplers and four identical arrayed-waveguide gratings (AWGs) with 16 channels. For the fabricated hybrid multiplexer, the excess loss and the crosstalk are about −7 and −10 dB, respectively. Better performances can be achieved by minimizing the imperfections (particularly in AWGs) in the fabrication processes. The present hybrid demultiplexer is scalable to have more channels by utilizing more wavelengths, modes, and polarizations.
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Silicon hybrid demultiplexer with 64 channels for wavelength/mode-division multiplexed on-chip optical Interconnects.
Optics letters, 2014Co-Authors: Jian Wang, Sitao Chen, Daoxin DaiAbstract:A monolithically integrated 64-channel hybrid demultiplexer on silicon is demonstrated experimentally to enable wavelength-division-multiplexing and mode-division-multiplexing simultaneously for realizing an ultra-large capacity optical-Interconnect Link. The present hybrid demultiplexer consists of a four-channel mode multiplexer realized with three cascaded asymmetrical directional-couplers and four identical arrayed-waveguide gratings (AWGs) with 16 channels. For the fabricated hybrid multiplexer, the excess loss and the crosstalk are about −7 and −10 dB, respectively. Better performances can be achieved by minimizing the imperfections (particularly in AWGs) in the fabrication processes. The present hybrid demultiplexer is scalable to have more channels by utilizing more wavelengths, modes, and polarizations.
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silicon multimode photonic integrated devices for on chip mode division multiplexed optical Interconnects
Progress in Electromagnetics Research-pier, 2013Co-Authors: Daoxin Dai, Jian Wang, Sailing HeAbstract:Multimode spatial-division multiplexing (SDM) technol- ogy has attracted much attention for its potential to enhance the ca- pacity of an optical-Interconnect Link with a single wavelength car- rier. For a mode-multiplexed optical-Interconnect Link, the functional elements are quite difierent from the conventional ones as multiple modes are involved. In this paper we give a review and discussion on multimode photonic integrated devices for mode-multiplexed optical- Interconnects. Light propagation and mode conversion in tapered waveguides as well as bent waveguides are discussed flrst. Recent progress on mode converter-(de)multiplexers is then reviewed. The demands of some functional devices used for mode-multiplexed optical- Interconnects are also discussed. In particular, the fabrication toler- ance is analyzed in detail for our hybrid demultiplexer, which enables mode-/polarization-division-(de)multiplexing simultaneously.
Chuanchuan Yang - One of the best experts on this subject based on the ideXlab platform.
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Deep belief network-hidden Markov model based nonlinear equalizer for VCSEL based optical Interconnect
Science China Information Sciences, 2020Co-Authors: Fukui Tian, Chuanchuan YangAbstract:The data center has developed rapidly over the past few years, leading to the demand for high speed data transmission. Vertical cavity surface emitting lasers (VCSELs) based optical Interconnect is evolving to 100 Gb/s and beyond, which makes nonlinear distortions difficult to be compensated or equalized by conventional equalizers. Moreover, the challenge becomes very complicated for conventional equalizers because of the presence of inter-symbol interference (ISI) together with the nonlinear distortions. So many neural network based DSP algorithms such as artificial neural network (ANN) have been proposed to mitigate the distortions. However, ANN has the limitations that samples relevant information is not considered, leading to degradation in ANNs performance and high computational complexity. In this paper, in order to maintain an excellent capability of mitigating nonlinear distortions like other neural network based equalizers while considering the samples relevant information to reduce the computational complexity, we propose a deep belief network-hidden Markov model (DBN-HMM) based nonlinear equalizer which is tested in a PAM-4 modulated VCSEL and multimode fiber (MMF) optical Interconnect Link experimentally. The BER performance can be greatly improved compared with conventional DSP algorithms. In addition, the computational complexity of DBN-HMM based equalizer can be about 41% lower than that of ANN based method with a similar BER performance.
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Gaussian mixture model-hidden Markov model based nonlinear equalizer for optical fiber transmission.
Optics express, 2020Co-Authors: Fukui Tian, Qingyi Zhou, Chuanchuan YangAbstract:The demand for high speed data transmission has increased rapidly over the past few years, leading to the development of the data center concept. As is known, nonlinear effects in optical fiber transmission systems are becoming significant with the development of transmission speed. Since it is difficult for conventional DSP algorithms to accurately capture these nonlinear distortions, many machine learning-based equalizers have been proposed. However, previous corresponding experiments mainly focused on achieving low BER while the computational complexity is much greater. In this paper, we propose a Gaussian mixture model (GMM)-hidden Markov model (HMM) based nonlinear equalizer, which utilizes the received signals' statistical characteristics as the priori information to reduce the computational complexity. The BER performance of the GMM-HMM based equalizer has been evaluated in a PAM-4 modulated VCSEL-MMF optical Interconnect Link, which shows an excellent capability of mitigating nonlinear distortions. In addition, the computational complexity of GMM-HMM based equalizer is about 73% lower than that of recurrent neural networks (RNN) based methods with similar BER performance.
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Low-Complexity Bi-Directional Recurrent Neural Network Equalizer for Short-Range Optical Interconnect Links
2019Co-Authors: Xin Qin, Chuanchuan Yang, Qingyi Zhou, Fukui Tian, Jiqiang Feng, Ziyu WangAbstract:We propose a BiRNN-based equalizer for short-range optical Interconnect Links. Compared with RNN-based equalizer, better BER performance and lower complexity are obtained on 56 Gb/s PAM-4 VCSEL-MMF based optical Interconnect Link over 100 m transmission.
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low computationally complex recurrent neural network for high speed optical fiber transmission
Optics Communications, 2019Co-Authors: Qingyi Zhou, Chuanchuan Yang, Anzhong Liang, Xiaolong Zheng, Zhangyuan ChenAbstract:Abstract The demand for high speed data transmission has increased rapidly over the past few years, leading to the development of the data center concept. Considering that vertical cavity surface emitting lasers (VCSELs) based optical Interconnect is evolving to 100 Gb/s, relative intensity noise and mode partition noise are becoming significant, which cannot be equalized by conventional equalizers efficiently. On the other hand, optical fiber suffers from inter-symbol interference (ISI) and nonlinear channel response, making the equalization process even more challenging. Recently, several machine learning techniques have already been applied to recover signal from nonlinear distortions. However, previous experiments mainly focused on achieving low BER and have neglected the computational complexity. In this paper, we have designed a recurrent neural network (RNN) based equalizer. The equalizer is tested over a PAM-4 modulated VCSEL-MMF optical Interconnect Link, and shows BER performance improvement over equalizers based on ANN. A variant, Half-RNN, is also proposed and tested, whose computational complexity is 70% lower than ANN with similar BER performance. Our experiments provide guidance for designing neural network structure when using deep learning for equalization, justifying the significance of our work.
Sitao Chen - One of the best experts on this subject based on the ideXlab platform.
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Silicon nanophotonic integrated devices enabling multiplexed on-chip optical Interconnects
Integrated Optics: Physics and Simulations II, 2015Co-Authors: Daoxin Dai, Jian Wang, Sitao ChenAbstract:Advanced multiplexing technologies including wavelength-division-multiplexing (WDM), polarization-division multiplexing (PDM), and mode-division multiplexing (MDM) have been utilized as a cost-effective solution to enhance the capacity of an optical-Interconnect Link. The on-chip (de)multiplexers, including WDM filters, PDM devices, and MDM devices, are the most important key components in a multi-channel multiplexed optical Interconnect system. Hybrid (de)multiplexer to enable various multiplexing technologies simultaneously are becoming more and more important to achieve many channels. In this paper we give a review for our recent work on silicon photonic integrated devices for realizing multi-channel multiplexed on-chip optical Interconnects.
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silicon hybrid demultiplexer with 64 channels for wavelength mode division multiplexed on chip optical Interconnects
Optics Letters, 2014Co-Authors: Jian Wang, Sitao Chen, Daoxin DaiAbstract:A monolithically integrated 64-channel hybrid demultiplexer on silicon is demonstrated experimentally to enable wavelength-division-multiplexing and mode-division-multiplexing simultaneously for realizing an ultra-large capacity optical-Interconnect Link. The present hybrid demultiplexer consists of a four-channel mode multiplexer realized with three cascaded asymmetrical directional-couplers and four identical arrayed-waveguide gratings (AWGs) with 16 channels. For the fabricated hybrid multiplexer, the excess loss and the crosstalk are about −7 and −10 dB, respectively. Better performances can be achieved by minimizing the imperfections (particularly in AWGs) in the fabrication processes. The present hybrid demultiplexer is scalable to have more channels by utilizing more wavelengths, modes, and polarizations.
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Silicon hybrid demultiplexer with 64 channels for wavelength/mode-division multiplexed on-chip optical Interconnects.
Optics letters, 2014Co-Authors: Jian Wang, Sitao Chen, Daoxin DaiAbstract:A monolithically integrated 64-channel hybrid demultiplexer on silicon is demonstrated experimentally to enable wavelength-division-multiplexing and mode-division-multiplexing simultaneously for realizing an ultra-large capacity optical-Interconnect Link. The present hybrid demultiplexer consists of a four-channel mode multiplexer realized with three cascaded asymmetrical directional-couplers and four identical arrayed-waveguide gratings (AWGs) with 16 channels. For the fabricated hybrid multiplexer, the excess loss and the crosstalk are about −7 and −10 dB, respectively. Better performances can be achieved by minimizing the imperfections (particularly in AWGs) in the fabrication processes. The present hybrid demultiplexer is scalable to have more channels by utilizing more wavelengths, modes, and polarizations.
Kc Claffy - One of the best experts on this subject based on the ideXlab platform.
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ANRW - TCP Congestion Signatures
Proceedings of the Applied Networking Research Workshop, 2018Co-Authors: Srikanth Sundaresan, Amogh Dhamdhere, Mark Allman, Kc ClaffyAbstract:We develop and validate Internet path measurement techniques to distinguish congestion experienced when a flow self-induces congestion in the path from when a flow is affected by an already congested path. One application of this technique is for speed tests, when the user is affected by congestion either in the last mile or in an Interconnect Link. This difference is important because in the latter case, the user is constrained by their service plan (i.e., what they are paying for), and in the former case, they are constrained by forces outside of their control. We exploit TCP congestion control dynamics to distinguish these cases for Internet paths that are predominantly TCP traffic. In TCP terms, we re-articulate the question: was a TCP flow bottlenecked by an already congested (possibly Interconnect) Link, or did it induce congestion in an otherwise idle (possibly a last-mile) Link? TCP congestion control affects the round-trip time (RTT) of packets within the flow (i.e., the flow RTT): an endpoint sends packets at higher throughput, increasing the occupancy of the bottleneck buffer, thereby increasing the RTT of packets in the flow. We show that two simple, statistical metrics derived from the flow RTT during the slow start period --- its coefficient of variation, and the normalized difference between the maximum and minimum RTT --- can robustly identify which type of congestion the flow encounters. We use extensive controlled experiments to demonstrate that our technique works with up to 90% accuracy. We also evaluate our techniques using two unique real-world datasets of TCP throughput measurements using Measurement Lab data and the Ark platform. We find up to 99% accuracy in detecting self-induced congestion, and up to 85% accuracy in detecting external congestion. Our results can benefit regulators of Interconnection markets, content providers trying to improve customer service, and users trying to understand whether poor performance is something they can fix by upgrading their service tier.
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Internet Measurement Conference - TCP congestion signatures
Proceedings of the 2017 Internet Measurement Conference, 2017Co-Authors: Srikanth Sundaresan, Amogh Dhamdhere, Mark Allman, Kc ClaffyAbstract:We develop and validate Internet path measurement techniques to distinguish congestion experienced when a flow self-induces congestion in the path from when a flow is affected by an already congested path. One application of this technique is for speed tests, when the user is affected by congestion either in the last mile or in an Interconnect Link. This difference is important because in the latter case, the user is constrained by their service plan (i.e., what they are paying for), and in the former case, they are constrained by forces outside of their control. We exploit TCP congestion control dynamics to distinguish these cases for Internet paths that are predominantly TCP traffic. In TCP terms, we re-articulate the question: was a TCP flow bottlenecked by an already congested (possibly Interconnect) Link, or did it induce congestion in an otherwise idle (possibly a last-mile) Link? TCP congestion control affects the round-trip time (RTT) of packets within the flow (i.e., the flow RTT): an endpoint sends packets at higher throughput, increasing the occupancy of the bottleneck buffer, thereby increasing the RTT of packets in the flow. We show that two simple, statistical metrics derived from the flow RTT during the slow start period---its coefficient of variation, and the normalized difference between the maximum and minimum RTT---can robustly identify which type of congestion the flow encounters. We use extensive controlled experiments to demonstrate that our technique works with up to 90% accuracy. We also evaluate our techniques using two unique real-world datasets of TCP throughput measurements using Measurement Lab data and the Ark platform. We find up to 99% accuracy in detecting self-induced congestion, and up to 85% accuracy in detecting external congestion. Our results can benefit regulators of Interconnection markets, content providers trying to improve customer service, and users trying to understand whether poor performance is something they can fix by upgrading their service tier.