| 1. |
- Hong, Xuezhi, et al.
(author)
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Passive Optical Interconnects Based on Cascading Wavelength Routing Devices for Datacenters : A Cross-Layer Perspective
- 2017
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In: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:4, s. C45-C53
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Journal article (peer-reviewed)abstract
- A general passive optical interconnect (POI) architecture based on cascading wavelength routing devices is proposed for datacenters. An analysis shows that with a proper port configuration, the logic topology of the proposed POI is equivalent to a DCell network, which has rich connectivity, leading to a high fault tolerance. Compared with the existing arrayed waveguide grating (AWG)-based architecture, such as H-LION, the proposed architecture has a higher AWG port utilization and lower cabling complexity that result in better scalability. Meanwhile, an impairment-aware scalability analysis is carried out to estimate the impact of in-band crosstalk on the size of the POI. Furthermore, a cross-layer investigation of the proposed POI provides a guideline to select proper physical-layer implementations, including optical interface structure and design of the transceiver, for acceptable network performance. The numerical results reveal that, with a moderate number of shortest paths K and degrees of node D, (a) the bidirectional optical interface is more suitable for large-scale datacenter networks than the unidirectional one, (b) an array of fixed receivers can be replaced by just a small number of tunable receivers with negligible degradation in network performance, and (c) decreasing 50% of the tuning range of the receivers causes only a minor increase of blocking probability, which demonstrates a good balance between the complexity of the transceiver design and network performance.
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| 3. |
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| 4. |
- Xue, Lei, 1992, et al.
(author)
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50-Gb/s Dispersion-unmanaged DMT Transmission with Injection Locked 10G-class 1.55-μm DML
- 2019
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In: Conference on Lasers and Electro-Optics OSA Technical Digest (Optical Society of America, 2019), paper SW4O.2. - : OSA - The Optical Society. - 9781557528209 ; Part F129-CLEO_SI 2019
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Conference paper (peer-reviewed)abstract
- We demonstrate 50-Gb/s DMT signal transmission over 20-km SMF by using a 10G-class 1.55-μm DML without optical dispersion compensation. Injection locking technique is introduced, which doubles system bandwidth and greatly suppresses DML chirp. © 2019 The Author(s)
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| 5. |
- Xue, Lei, 1992, et al.
(author)
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Optics-simplified DSP for 50 Gb/s PON downstream transmission using 10 Gb/s optical devices
- 2020
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In: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 38:3, s. 583-589
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Journal article (peer-reviewed)abstract
- Directly-modulated laser (DML) is widely employed in intensity modulation and direct detection (IMDD) system due to its low cost and high output power. However, the corresponding frequency chirp is regarded as one of the main disadvantages for its application in passive optical networks (PONs). In this paper, we theoretically analyze the frequency response evolution of DML based system under different chirp and dispersion conditions, proving that the system bandwidth can be improved by interactions between negative dispersion and DML chirp. Based on this concept, we experimentally demonstrated downstream 50 Gb/s PAM4 signal transmission over 20 km single-mode fiber (SMF) access based on the 10 Gb/s DML operating at 1310 nm and avalanche photodiode (APD). A dispersion-shifted fiber (DSF) providing -150 ps/nm dispersion at 1310 nm in the optical line terminal (OLT) is used to pre-equalize the frequency response of bandwidth-limited directly modulated signals in the optical domain. Thanks to our proposed dispersion-supported equalization (DSE) technique, the system bandwidth can be improved by 5 GHz. Feed-forward equalization (FFE), decision feedback equalization (DFE) and Volterra filter are employed to evaluate the signal performance improvement, respectively. By evaluating the receiver sensitivity, the DSE combined with FFE scheme shows 2 dB improvement than the complex Volterra algorithm, indicating its potential to reduce the complexity of digital signal processing (DSP) and therefore a lower cost and power consumption in PON.
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| 6. |
- Xue, Lei, 1992, et al.
(author)
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SOA pattern effect mitigation by neural network based pre-equalizer for 50G PON
- 2021
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In: Optics Express. - 1094-4087 .- 1094-4087. ; 29:16, s. 24714-24722
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Journal article (peer-reviewed)abstract
- Semiconductor optical amplifier (SOA) is widely used for power amplification in O-band, particularly for passive optical networks (PONs) which can greatly benefit its advantages of simple structure, low power consumption and integrability with photonics circuits. However, the annoying nonlinear pattern effect degrades system performance when the SOA is needed as a pre-amplifier in PONs. Conventional solutions for pattern effect mitigation are either based on optical filtering or gain clamping. They are not simple or sufficiently flexible for practical deployment. Neural network (NN) has been demonstrated for impairment compensation in optical communications thanks to its powerful nonlinear fitting ability. In this paper, for the first time, NN-based equalizer is proposed to mitigate the SOA pattern effect for 50G PON with intensity modulation and direct detection. The experimental results confirm that the NN-based equalizer can effectively mitigate the SOA nonlinear pattern effect and significantly improve the dynamic range of receiver, achieving 29-dB power budget with the FEC limit at 1e-2. Moreover, the well-trained NN model in the receiver side can be directly placed at the transmitter in the optical line terminal to pre-equalize the signal for transmission so as to simplify digital signal processing in the optical network unit.
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| 7. |
- Yang, Yi, et al.
(author)
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Network performance analysis of an AWG-based passive optical interconnect for datacenters
- 2016
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In: 2016 Asia Communications and Photonics Conference, ACP 2016. - : OSA - The Optical Society.
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Conference paper (peer-reviewed)abstract
- AWG-based passive optical interconnects (POIs) are considered a high-capacity and energy-efficient solution for datacenter networks. We concentrate on a cascaded AWG-based POI and analyze network performance to gain insights on efficiency of such an architecture.
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| 8. |
- Yi, Jiajia, et al.
(author)
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Electrostatic Interactions Accelerating Water Oxidation Catalysis via Intercatalyst O-O Coupling
- 2021
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In: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 143:6, s. 2484-2490
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Journal article (peer-reviewed)abstract
- Intercatalyst coupling has been widely applied in the functional mimics for binuclear synergy in natural metal enzymes. Herein, we introduce two facile and effective design strategies, which facilitate the coupling of two catalytic units via electrostatic interactions. The first system is based on a catalyst molecule functionalized with both a positively charged and a negatively charged group in the structure being able to pair with each other in an antiparallel manner arranged by electrostatic interactions. The other system consists of a mixture of two different of catalysts modified with either positively or negatively charged groups to generate intermo-lecular electrostatic interactions. Applying these designs to Ru(bda) (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) water-oxidation catalysts improved the catalytic performance by more than an order of magnitude. The intermolecular electrostatic interactions in these two systems were fully identified by H-1 NMR, TEM, SAXS, and electrical conductivity experiments. Molecular dynamics simulations further verified that electrostatic interactions contribute to the formation of prereactive dimers, which were found to play a key role in dramatically improving the catalytic performance. The successful strategies demonstrated here can be used in designing other intercatalyst coupling systems for activation and formation of small molecules and organic synthesis.
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| 9. |
- Yi, Y., et al.
(author)
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Service chain placement in server-centric optical datacenter networks
- 2017
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In: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781557528209
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Conference paper (peer-reviewed)abstract
- We propose and compare several heuristics service chain (SC) placement algorithms tailored for the server-centric optical interconnect architecture, providing a guideline on how to efficiently place SCs in such an optical datacenter network.
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| 10. |
- Zhang, Yaoxin, et al.
(author)
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Could social robots facilitate children with autism spectrum disorders in learning distrust and deception?
- 2019
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In: Computers in Human Behavior. - : Elsevier BV. - 0747-5632. ; 98, s. 140-149
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Journal article (peer-reviewed)abstract
- Social robots have been increasingly involved in our daily lives and provide a new environment for children's growth. The current study aimed to examine how children with and without Autism Spectrum Disorders (ASD)learned complex social rules from a social robot through distrust and deception games. Twenty children with ASD between the ages of 5–8 and 20 typically-developing (TD)peers whose age and IQ were matched participated in distrust and deception tasks along with an interview about their perception of the human-likeness of the robot. The results demonstrated that: 1)children with ASD were slower to learn to and less likely to distrust and deceive a social robot than TD children and 2)children with ASD who perceived the robot to appear more human-like had more difficulty in learning to distrust the robot. Besides, by comparing to a previous study the results showed that children with ASD appeared to have more difficulty in learning to distrust a human compared to a robot, particularly in the early phase of learning. Overall, our study verified that social robots could facilitate children with ASD's learning of some social rules and showed that children's perception of the robot plays an important role in their social learning, which provides insights on robot design and its clinical applications in ASD intervention.
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