In this paper,recent advances in underwater wireless optical communication(UWOC)are reviewed for both LED-and LD-based systems,mainly from a perspective of advanced modulation formats.Volterra series-based nonlinear e...In this paper,recent advances in underwater wireless optical communication(UWOC)are reviewed for both LED-and LD-based systems,mainly from a perspective of advanced modulation formats.Volterra series-based nonlinear equalizers,which can effectively counteract the nonlinear impairments induced by the UWOC system components,are discussed and experimentally demonstrated.Both the effectiveness and robustness of the proposed Volterra nonlinear equalizer in UWOC systems under different water turbidities are validated.To further approach the Shannon capacity limit of the UWOC system,the probabilistic constellation shaping technique is introduced,which can overcome the inherent gap between a conventional regular quadrature amplitude modulation(QAM)format and the Shannon capacity of the channel.The experimental results have shown a significant system capacity improvement compared to the cases using a regular QAM.展开更多
In this paper,we present the experimental results for integrated photonic devices optimized with an energyconstrained inverse design method.When this constraint is applied,optimizations are directed to solutions that ...In this paper,we present the experimental results for integrated photonic devices optimized with an energyconstrained inverse design method.When this constraint is applied,optimizations are directed to solutions that contain the optical field inside the waveguide core medium,leading to more robust designs with relatively larger minimum feature size.We optimize three components:a mode converter(MC),a 1310 nm/1550 nm wavelength duplexer,and a three-channel C-band wavelength demultiplexer for coarse wavelength division multiplexing(CWDM)application with 50 nm channel spacing.The energy constraint leads to nearly binarized structures without applying independent binarization stage.It also reduces the appearance of small features.In the MC,well-binarized design,improved insertion loss,and cross talk are obtained as a result.Furthermore,the proposed constraint improves the robustness to fabrication imperfections as shown in the duplexer design.With energy constraint optimization,the corresponding spectrum shifts for the duplexer under±10 nm dimensional variations are reduced from 105 nm to 55 nm and from 72 nm to 60 nm for the 1310 nm and 1550 nm channel,respectively.In the CWDM demultiplexer,robustness toward±10 nm fabrication error is improved by a factor of 2.The introduction of the energy constraint into topological optimization demonstrates computational gain with better-performing designs.展开更多
基金supported in part by the National Key Research and Development Program of China(No.2018YFC1407500)National Natural Science Foundation of China(NSFC)(No.11621101)the funding of Ningbo Research Institute
文摘In this paper,recent advances in underwater wireless optical communication(UWOC)are reviewed for both LED-and LD-based systems,mainly from a perspective of advanced modulation formats.Volterra series-based nonlinear equalizers,which can effectively counteract the nonlinear impairments induced by the UWOC system components,are discussed and experimentally demonstrated.Both the effectiveness and robustness of the proposed Volterra nonlinear equalizer in UWOC systems under different water turbidities are validated.To further approach the Shannon capacity limit of the UWOC system,the probabilistic constellation shaping technique is introduced,which can overcome the inherent gap between a conventional regular quadrature amplitude modulation(QAM)format and the Shannon capacity of the channel.The experimental results have shown a significant system capacity improvement compared to the cases using a regular QAM.
基金National Research Council Canada(AI for Design and HTSN Challenge Programs),China Scholarship Council。
文摘In this paper,we present the experimental results for integrated photonic devices optimized with an energyconstrained inverse design method.When this constraint is applied,optimizations are directed to solutions that contain the optical field inside the waveguide core medium,leading to more robust designs with relatively larger minimum feature size.We optimize three components:a mode converter(MC),a 1310 nm/1550 nm wavelength duplexer,and a three-channel C-band wavelength demultiplexer for coarse wavelength division multiplexing(CWDM)application with 50 nm channel spacing.The energy constraint leads to nearly binarized structures without applying independent binarization stage.It also reduces the appearance of small features.In the MC,well-binarized design,improved insertion loss,and cross talk are obtained as a result.Furthermore,the proposed constraint improves the robustness to fabrication imperfections as shown in the duplexer design.With energy constraint optimization,the corresponding spectrum shifts for the duplexer under±10 nm dimensional variations are reduced from 105 nm to 55 nm and from 72 nm to 60 nm for the 1310 nm and 1550 nm channel,respectively.In the CWDM demultiplexer,robustness toward±10 nm fabrication error is improved by a factor of 2.The introduction of the energy constraint into topological optimization demonstrates computational gain with better-performing designs.
