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Volume  期 1，2026 2026年第卷第1期

    YANG Kexin, HUANG Tingting, ZHOU Peng, LI Xin, YAN Ying, LI Yongcheng

    DOI：10.13756/j.gtxyj.2026.240241
    摘要：ObjectiveThe wavelength conflict of different optical channels tends to occur in the All-Optical Spine-Leaf (AOSL) Data Center Network (DCN) that adopts a multi-stage Wavelength Selective Switches (WSS) cascading. This will cause a large number of service requests to be blocked, thus significantly influencing the spectral utilization efficiency of the DCN. To address this issue, Tunable Wavelength Conversion (TWC) modules can be used in the AOSL DCN to enable the conversion of each wavelength to any other wavelength whenever wavelength conflict occurs. However, this will also significantly increase the total cost of the AOSL DCN. Therefore, this paper aims to find a balance between network performance and networking cost by developing the AOSL DCNs with limited wavelength conversion.MethodsIn this paper, we propos two different architectures for the AOSL DCN with limited wavelength conversion, including wavelength conversion allowed on partial WSS and wavelength conversion allowed on specific wavelengths, respectively. The former one deploys the TWC modules with full wavelength conversion capacity, merely for certain spine WSSs. In contrast, the latter one deploys TWC modules that are configured to permit specific wavelength conversion for all of the Spine WSSs. In addition, this paper also proposes corresponding Routing, Wavelength and Time Slot Allocation (RWTA) algorithms for the static lightpath service deployment problem of these two AOSL DCN architectures.ResultsSimulation results show that both network architectures proposed in this paper can achieve performance close to that of the all-optical spine-leaf data center network with full wavelength conversion capabilities in terms of overall Task Completion Time (TCT) and total WSS reconfiguration times.ConclusionOur AOSL DCN proposed with limited wavelength conversion effectively guarantees network performance while reducing the networking costs.  
    关键词：data center;wavelength switched network;wavelength conversion;RWTA   
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    更新时间：2026-03-03

    LIU Ziyue, LI Zhengxuan, YANG Qinyao, GAO Qi, WANG Liang, SONG Yingxiong

    DOI：10.13756/j.gtxyj.2026.240177
    摘要：ObjectiveTwo enhanced differential schemes have been proposed to improve the feasibility of differential modulation in the uplink transmission scenario for multi-user coherent systems.MethodsLeveraging the inherent capability of 16 Differential Amplitude and Phase Shift Keying (DAPSK) to automatically eliminate phase difference within quasi-steady-state Orthogonal Frequency Division Multiplexing (OFDM) frames, a scheme utilizing different-order differential phase joint modulation is proposed. Further performance enhancements are achieved through the incorporation of a scrambler.ResultsCompared with 16DAPSK modulation, the proposed two modulation schemes bring about 2 and 3 dB sensitivity improvement to the system, respectively.ConclusionThe Bit Error Rate (BER) performance of both the joint modulation scheme and the joint modulation scheme with scrambler surpasses that of the original one, thereby enhancing the data transmission reliability.  
    关键词：OFDM;DAPSK;phase noise compensation;linewidth tolerance   
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    更新时间：2026-03-03

    LU Hui, LIU Fengqing, ZHAO Xiangyu

    DOI：10.13756/j.gtxyj.2026.240146
    摘要：ObjectiveTo address the issues of load imbalance, low resource efficiency, the “tidal effect” of periodic fluctuations in traffic geography and time domain distribution in current time-wavelength division networks, this paper proposes a flexible Multi-Time Wavelength Division Multiplexing (TWDM)-Passive Optical Network (PON) scheme based on Arrayed Waveguide Grating (AWG).MethodsThis system combines fixed and tunable wavelength lasers, leveraging the routing characteristics of AWG to dynamically adjust the allocated bandwidth for each PON based on real-time network load, enabling flexible wavelength resource allocation while maintaining the passivity of the optical distribution network.ResultsThe system achieves wavelength sharing and efficient resource allocation, catering to diverse bandwidth demands of different users. Simulation results show that with a single wavelength transmission rate of 10 Gbit/s, the downlink transmission power budget exceeds 34 dB, and the system split ratio can reach 1∶512 at a maximum transmission distance of 30 km. It is indicated that the design scheme proposed in this paper can not only effectively improve resource utilization and optimize network transmission performance, but also take into account the economy and reliability of system deployment.ConclusionIt can adapt to the diverse high-speed service requirements such as 4K/8K ultra-high-definition video and cloud computing, which provides a feasible technical path for the next-generation optical access network to address the problem of uneven traffic distribution with good practical application value.  
    关键词：TWDM-PON;AWG;wavelength sharing;wavelength routing   
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    更新时间：2026-03-03

    KOU Yunjie, FAN Yanan, ZHU Yanbing, SHANG Jiaqi, WANG Feiran

    DOI：10.13756/j.gtxyj.2026.240144
    摘要：ObjectiveQuantum communication is an emerging mode of communication with broad application prospects, combining with classical information science and technology. It offers unconditional security and efficient transmission of information, making it a hot research topic in todayƳs communication field. High-dimensional quantum entanglement often exhibits strong nonlocality, enhancing the security in quantum communication processes and playing a crucial role in quantum communication and computing. To meet the demand for high-dimensional entangled states in quantum information science, this paper proposes a method for generating high-dimensional Bell states based on the Orbital Angular Momentum (OAM) of photons, capable of producing the complete set of Bell state basis vectors with high fidelity.MethodsInitially, the Spontaneous Parametric Down-Conversion (SPDC) process involving photon OAM is studied. Furthermore, a Genetic Algorithm (GA) is employed to optimize the quantum state of the pump light, aiming to obtain the required high-dimensional maximally entangled states. We analyze the characteristics of Laguerre-Gaussian (LG) beams in detail and explore their application in the SPDC process. By optimizing the parameters of the pump light, maximally entangled states are generated in three-dimensional, four-dimensional, and five-dimensional spaces.ResultsA comparison of the spatial mode spectral distribution shows that the optimized entangled states possess higher fidelity to the target states. Additionally, by simulating the generation of 16 Bell states, it is verified that the produced quantum states form a complete basis for a four-dimensional Hilbert space.ConclusionThe proposed scheme not only effectively generates high-dimensional entangled states but also enables longer-distance quantum communication and potentially global quantum communication systems. Moreover, it provides new avenues for the application of high-dimensional entangled states in the fields of quantum communication and computing, significantly contributing to the advancement of quantum information science.  
    关键词：quantum communication;photon OAM;high-dimensional entangled states   
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    更新时间：2026-03-03
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   Study on Optical Communications

 

 

 

 

 

 

 

Bimonthly, started in 1975

Governed by，China Information Communication Technologies Group Corporation (CICT)

Sponsored by：Wuhan Research Institute of Post & Telecommunications Co., Ltd.

Publisher：Editorial Department of Study on Optical Communications

 

Honorary Editor-in-Chief：YU Shao-hua

Editor-in-Chief：LI Han-bing

Executive Editor-in-Chief：XIAO Xi

Director：WANG Xi

 

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