A mutually pumped phase conjugator with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate is reported,in which both incoherent beams are incident upon the negative c face and th...A mutually pumped phase conjugator with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate is reported,in which both incoherent beams are incident upon the negative c face and they travel in geometric paths similar to the outline of two arches.The maximum reflectivity attains 21%.The tolerance of the output to both incident angles and positions is assessed.No apparent cross talk is observed.A cross-readout mechanism is also used to explain phase-conjugate reflectivity production.It is verified that the configuration can be realized easily for a crystal with two longer a sides.展开更多
A mutually pumped phase conjugator is demonstrated with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate,in which the beams travel in a geometric path similar to the outline of...A mutually pumped phase conjugator is demonstrated with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate,in which the beams travel in a geometric path similar to the outline of a sickle.The maximum reflectivity is up to 168%.Faster response times are measured and are also simulated as a function of incident beam power ratio.Four available input geometries are found.The phase conjugation signals exist wide range of angular and positional alignment.No apparent cross talk is observed.The faster build-up process of phase conjugation beams is tentatively explained.展开更多
流星余迹通信是一种重要的应急通信方式。其通信网络具有传输延时长和链路间歇中断的特点,适用于这种特殊网络的路由算法具有明显的针对性,有待深入研究。文中在研究流星余迹网络拓扑结构的基础上,基于OPNET仿真软件构建流星余迹组网模...流星余迹通信是一种重要的应急通信方式。其通信网络具有传输延时长和链路间歇中断的特点,适用于这种特殊网络的路由算法具有明显的针对性,有待深入研究。文中在研究流星余迹网络拓扑结构的基础上,基于OPNET仿真软件构建流星余迹组网模型,结合适用于DTN(Delay Tolerant Network)网络的ED(Earliest Delivery)算法和EDLQ(Earliest Delivery with Local Queue)算法的特点,分析通信时延模型,提出一种改进的OED(Optimistic Earliest Delivery)算法。基于已建立的模型对数据传输成功率和网络吞吐量进行仿真。仿真结果表明,OED算法在组网网络的数据吞吐量和数据传输成功率方面优于ED算法和EDLQ算法,能够避免因队列溢出导致的数据包丢失;通过增大节点容量,OED算法的数据通过率相对于ED算法和EDLQ算法分别提升了20%和8%;路由算法的选择不影响流星余迹节点间链路的平均持续时间和平均中断等待时间。OED算法在流星余迹网络中具有较强的适应性,能够为流星余迹组网的建设提供参考。展开更多
基金Supported by the Grant for a Key Research Project in Climbing Program from the State Science and Technology Commission of China.
文摘A mutually pumped phase conjugator with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate is reported,in which both incoherent beams are incident upon the negative c face and they travel in geometric paths similar to the outline of two arches.The maximum reflectivity attains 21%.The tolerance of the output to both incident angles and positions is assessed.No apparent cross talk is observed.A cross-readout mechanism is also used to explain phase-conjugate reflectivity production.It is verified that the configuration can be realized easily for a crystal with two longer a sides.
基金Supported by a grant for a Key Research Project in Climbing Program from the State Science and Technology Commission of China。
文摘A mutually pumped phase conjugator is demonstrated with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate,in which the beams travel in a geometric path similar to the outline of a sickle.The maximum reflectivity is up to 168%.Faster response times are measured and are also simulated as a function of incident beam power ratio.Four available input geometries are found.The phase conjugation signals exist wide range of angular and positional alignment.No apparent cross talk is observed.The faster build-up process of phase conjugation beams is tentatively explained.
文摘流星余迹通信是一种重要的应急通信方式。其通信网络具有传输延时长和链路间歇中断的特点,适用于这种特殊网络的路由算法具有明显的针对性,有待深入研究。文中在研究流星余迹网络拓扑结构的基础上,基于OPNET仿真软件构建流星余迹组网模型,结合适用于DTN(Delay Tolerant Network)网络的ED(Earliest Delivery)算法和EDLQ(Earliest Delivery with Local Queue)算法的特点,分析通信时延模型,提出一种改进的OED(Optimistic Earliest Delivery)算法。基于已建立的模型对数据传输成功率和网络吞吐量进行仿真。仿真结果表明,OED算法在组网网络的数据吞吐量和数据传输成功率方面优于ED算法和EDLQ算法,能够避免因队列溢出导致的数据包丢失;通过增大节点容量,OED算法的数据通过率相对于ED算法和EDLQ算法分别提升了20%和8%;路由算法的选择不影响流星余迹节点间链路的平均持续时间和平均中断等待时间。OED算法在流星余迹网络中具有较强的适应性,能够为流星余迹组网的建设提供参考。
