电场耦合式无线电能传输(electric-field coupled wireless power transfer,ECPT)系统因电磁干扰小、对极板间金属异物不敏感、无涡流损耗等优点而受到广泛的关注,然而其输出功率和传输效率会随着发射侧极板和接收极板之间距离的增加而...电场耦合式无线电能传输(electric-field coupled wireless power transfer,ECPT)系统因电磁干扰小、对极板间金属异物不敏感、无涡流损耗等优点而受到广泛的关注,然而其输出功率和传输效率会随着发射侧极板和接收极板之间距离的增加而急剧下降。为了解决上述问题,提出一种基于宇称时间(parity time,PT)对称的ECPT系统。其中通过电力电子变换器提供非线性饱和增益,以满足PT对称条件。分别建立基于PT对称的并联并联(parallel-parallel,PP)型和串联串联(series-series,SS)型2种补偿拓扑的ECPT系统电路模型,推导了2种不同拓扑结构ECPT系统的工作频率和传输特性,比较并讨论2种不同拓扑结构ECPT系统的适用场合。分析结果表明,当耦合极板间的距离(极板耦合系数)发生变化时,所提出的系统均能在满足PT对称条件下保持恒功率和恒效率输出。仿真结果验证了理论分析的正确性。展开更多
A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetr...A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.展开更多
含中继线圈的无线电能传输(wireless power transfer,WPT)技术是提高系统传输距离的有效解决方案。基于宇称时间(parity time,PT)对称原理,含中继线圈的多线圈WPT系统在传输距离变化时具有恒功率恒效率的输出特性。已有的多线圈PT对称...含中继线圈的无线电能传输(wireless power transfer,WPT)技术是提高系统传输距离的有效解决方案。基于宇称时间(parity time,PT)对称原理,含中继线圈的多线圈WPT系统在传输距离变化时具有恒功率恒效率的输出特性。已有的多线圈PT对称系统工作时需要满足相邻线圈之间距离相等条件,限制多线圈PT对称系统的实用性。为此,该文提出一种发射端含可变参数的三线圈PT对称WPT系统,当系统不满足距离相等条件时,通过调节可变电感及可变电容使系统满足PT对称条件。该文推导系统的输出特性表达式,论述可变参数的构造、控制方法,并搭建所提系统的实验平台。实验结果表明,相较于已有系统,所提系统在不满足距离相等条件时,具有恒功率恒效率的输出特性。展开更多
基金supported by the National Natural Science Foundation of China (21002006,20452002)Special Program for Key Basic Research of the Ministry of Science and Technology,China (2004-973-36)~~
文摘A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.
文摘含中继线圈的无线电能传输(wireless power transfer,WPT)技术是提高系统传输距离的有效解决方案。基于宇称时间(parity time,PT)对称原理,含中继线圈的多线圈WPT系统在传输距离变化时具有恒功率恒效率的输出特性。已有的多线圈PT对称系统工作时需要满足相邻线圈之间距离相等条件,限制多线圈PT对称系统的实用性。为此,该文提出一种发射端含可变参数的三线圈PT对称WPT系统,当系统不满足距离相等条件时,通过调节可变电感及可变电容使系统满足PT对称条件。该文推导系统的输出特性表达式,论述可变参数的构造、控制方法,并搭建所提系统的实验平台。实验结果表明,相较于已有系统,所提系统在不满足距离相等条件时,具有恒功率恒效率的输出特性。
