The effect of channel-width chirping on near- and far-field intensity patterns of the six supermodes was investigated. The supermode discrimination was evaluated in various channel-chirped index guided laser arrays. T...The effect of channel-width chirping on near- and far-field intensity patterns of the six supermodes was investigated. The supermode discrimination was evaluated in various channel-chirped index guided laser arrays. The results show that the linearly channel-chirped laser array has very good supermode discrimination which is better than that of a uniform laser array, the V channel-chirped laser array has the smallest radiation angle of the fundamental supermode among the calculated arrays, and the asymmetrically V channel-chirped array has a very small radiation angle of the fundamental supermode, which is smaller than that of the uniform array and also allows for very good fundamental supermode discrimination against the higher-order supermodes, which is better than that of the V channel-chirped laser array.展开更多
The dynamic gain of a few-mode erbium-doped fiber amplifier(FM-EDFA)is vital for the long-haul mode division multiplexing(MDM)transmission.Here,we investigate the mode-dependent dynamic gain of an FM-EDFA under variou...The dynamic gain of a few-mode erbium-doped fiber amplifier(FM-EDFA)is vital for the long-haul mode division multiplexing(MDM)transmission.Here,we investigate the mode-dependent dynamic gain of an FM-EDFA under various manipulations of the pump mode.First,we numerically calculate the gain variation with respect to the input signal power,where a modedependent saturation input power occurs under different pump modes.Even under the fixed intensity profile of the pump laser,the saturation input power of each spatial mode is different.Moreover,high-order mode pumping leads to a compression of the linear amplification region,even though it is beneficial for the mitigation of the differential modal gain(DMG)arising in all guided modes.Then,we develop an all-fiber 3-mode EDFA,where the fundamental mode of the pump laser can be efficiently converted to the LP_(11)mode using the all-fiber mode-selective coupler(MSC).In comparison with the traditional LP_(01)pumping scheme,the DMG at 1550 nm can be mitigated from 1.61 dB to 0.97 dB under the LP_(11)mode pumping,while both an average gain of 19.93 dB and a DMG of less than 1 dB can be achieved from 1530 nm to 1560 nm.However,the corresponding signal input saturation powers are reduced by 0.3 dB for the LP_(01)mode and 1.6 dB for the LP_(11)mode,respectively.Both theoretical and experimental results indicate that a trade-off occurs between the DMG mitigation and the extension of the linear amplification range when the intensity profile of pump laser is manipulated.展开更多
研究了使用垂直线列阵情况下,浅海环境中的模态空间检测器(modal space detector,MSD)的检测性能.推导了MSD的处理增益,结果表明其处理增益随波导环境中传播模态数的增多而减小,进而其检测性能也随之下降.利用各阶模态深度函数之间的正...研究了使用垂直线列阵情况下,浅海环境中的模态空间检测器(modal space detector,MSD)的检测性能.推导了MSD的处理增益,结果表明其处理增益随波导环境中传播模态数的增多而减小,进而其检测性能也随之下降.利用各阶模态深度函数之间的正交性,将MSD分解为若干阶模态子空间检测器(modal subspace detector,MSSD).推导了各阶MSSD的处理增益,发现其随各阶模态衰减系数的增大而减小.根据各阶模态的衰减规律设计加权系数,提出一种加权模态子空间检测器(weighted modal subspace detector,WMSSD).以处理增益作为比较参量,通过理论和仿真实验分析了声源位置和声速剖面对WMSSD检测性能的影响.结果表明:(1)当声源位于负梯度声速波导的近海面区域和正梯度声速波导的近海底区域时,由于低阶模态深度函数存在反转点,WMSSD的处理增益弱于MSD,而当声源位于其他大部分观测区域时,WMSSD的处理增益都优于或显著优于MSD;(2)在等声速梯度波导中,各阶模态深度函数不存在反转点,在所有观测区域WMSSD的处理增益都显著优于MSD.展开更多
本文采用改进的化学气相沉积(modified chemical vapor deposition,MCVD)法制备了一种新型少模光纤DD硫化铅(Pb S)掺杂少模光纤,研究了该光纤的荧光特性,并基于空间光调制器搭建了少模光纤放大系统,测量了光纤的模式增益特性。实验结果...本文采用改进的化学气相沉积(modified chemical vapor deposition,MCVD)法制备了一种新型少模光纤DD硫化铅(Pb S)掺杂少模光纤,研究了该光纤的荧光特性,并基于空间光调制器搭建了少模光纤放大系统,测量了光纤的模式增益特性。实验结果表明:在980 nm激光泵浦下,该光纤表现出超宽带近红外发光,光谱范围为1 050~1 650 nm;在1 540~1 560 nm波段范围内,实现了LP和LP模式放大,平均模式开关增益为4.5 d B,差模增益小于0.6 d B。该光纤为模分复用系统实现宽带模式放大提供了可行性。展开更多
Considering spectrum tilt due to signal-to-signal Raman scattering (SSRS) in backward distributed fiber Raman amplifiers (B-DFRA),an inverse tilted on-off gain profile is adopted to achieve flat net gain.A simple appr...Considering spectrum tilt due to signal-to-signal Raman scattering (SSRS) in backward distributed fiber Raman amplifiers (B-DFRA),an inverse tilted on-off gain profile is adopted to achieve flat net gain.A simple approximate linear relationship of pump power at each wavelength versus on-off gain level and tilt was derived numerically and experimentally so that a novel control method was established.Since there are only 3 pre-determinable constants required for individual pump wave,it is easy to be realized.As an example,maximum errors less than 0.2 and 0.4 dB respectively for average gain and gain tilt were achieved over C+L band in 100-km back-pumped standard single-mode fiber (SMF) experimentally.展开更多
STATCOM以快速无功控制稳定电压,但缺乏协调配合会产生交互影响。采用模态分析与相对增益矩阵(relative gain array,RGA)结合的方法进行交互影响分析,借助精确反馈线性化改进内层电流控制。建立多STATCOM系统的状态空间表达式,通过模态...STATCOM以快速无功控制稳定电压,但缺乏协调配合会产生交互影响。采用模态分析与相对增益矩阵(relative gain array,RGA)结合的方法进行交互影响分析,借助精确反馈线性化改进内层电流控制。建立多STATCOM系统的状态空间表达式,通过模态分析确定系统出现负阻尼振荡模式的控制器参数;结合状态空间表达式系数矩阵,求解相对增益矩阵,研究输入信号及电气距离与交互影响的关联机理;结果表明STATCOM控制器比例增益设置会引入新的局部振荡模式,引起低频功率振荡;而参考电压与电气耦合程度是负交互影响产生的重要因素。针对传统内环电流控制,利用非线性控制理论对其改进,设计输入状态反馈线性化控制器;借助线性二次型控制理论确定状态反馈矩阵,推导最优控制律,实现受控状态对期望状态的最优逼近;仿真结果表明非线性控制器能有效改善参考信号阶跃引起的功率波动,显著提高系统阻尼。展开更多
阶梯式掺杂和多环式掺杂设计的掺铒光纤(EDFs)结构复杂,采用改进化学气相沉积法(MCVD)制备困难。为此,将两段铒离子分别为中心掺杂和环形掺杂的掺铒光纤级联构成四线偏振模信号光放大器。该结构放大器使中心模式信号光(LP_(01)模和LP_(...阶梯式掺杂和多环式掺杂设计的掺铒光纤(EDFs)结构复杂,采用改进化学气相沉积法(MCVD)制备困难。为此,将两段铒离子分别为中心掺杂和环形掺杂的掺铒光纤级联构成四线偏振模信号光放大器。该结构放大器使中心模式信号光(LP_(01)模和LP_(02)模)和离心模式信号光(LP_(11)模和LP_(21)模)分别在中心掺杂铒光纤和环形掺杂铒光纤中获得主要增益。基于一种改进遗传算法(GA),对该放大器两段掺铒光纤的长度和铒离子掺杂半径进行优化。结果显示,仅用270m W LP_(11)模抽运光对该级联结构放大器进行抽运,四线偏振模信号光可获得20dB的平均增益,且模式相关增益(DMG)不超过3.5dB。展开更多
文摘The effect of channel-width chirping on near- and far-field intensity patterns of the six supermodes was investigated. The supermode discrimination was evaluated in various channel-chirped index guided laser arrays. The results show that the linearly channel-chirped laser array has very good supermode discrimination which is better than that of a uniform laser array, the V channel-chirped laser array has the smallest radiation angle of the fundamental supermode among the calculated arrays, and the asymmetrically V channel-chirped array has a very small radiation angle of the fundamental supermode, which is smaller than that of the uniform array and also allows for very good fundamental supermode discrimination against the higher-order supermodes, which is better than that of the V channel-chirped laser array.
基金supported by the National Key R&D Program of China(No.2018YFB1800903)the National Natural Science Foundation of China(No.U22A2087)+1 种基金the Guangdong Introducing Innovative and Entrepreneurial Teams of the Pearl River Talent Recruitment Program(No.2021ZT09X044)the Guangdong Provincial Key Laboratory of Photonics Information Technology(No.2020B121201011)。
文摘The dynamic gain of a few-mode erbium-doped fiber amplifier(FM-EDFA)is vital for the long-haul mode division multiplexing(MDM)transmission.Here,we investigate the mode-dependent dynamic gain of an FM-EDFA under various manipulations of the pump mode.First,we numerically calculate the gain variation with respect to the input signal power,where a modedependent saturation input power occurs under different pump modes.Even under the fixed intensity profile of the pump laser,the saturation input power of each spatial mode is different.Moreover,high-order mode pumping leads to a compression of the linear amplification region,even though it is beneficial for the mitigation of the differential modal gain(DMG)arising in all guided modes.Then,we develop an all-fiber 3-mode EDFA,where the fundamental mode of the pump laser can be efficiently converted to the LP_(11)mode using the all-fiber mode-selective coupler(MSC).In comparison with the traditional LP_(01)pumping scheme,the DMG at 1550 nm can be mitigated from 1.61 dB to 0.97 dB under the LP_(11)mode pumping,while both an average gain of 19.93 dB and a DMG of less than 1 dB can be achieved from 1530 nm to 1560 nm.However,the corresponding signal input saturation powers are reduced by 0.3 dB for the LP_(01)mode and 1.6 dB for the LP_(11)mode,respectively.Both theoretical and experimental results indicate that a trade-off occurs between the DMG mitigation and the extension of the linear amplification range when the intensity profile of pump laser is manipulated.
文摘Considering spectrum tilt due to signal-to-signal Raman scattering (SSRS) in backward distributed fiber Raman amplifiers (B-DFRA),an inverse tilted on-off gain profile is adopted to achieve flat net gain.A simple approximate linear relationship of pump power at each wavelength versus on-off gain level and tilt was derived numerically and experimentally so that a novel control method was established.Since there are only 3 pre-determinable constants required for individual pump wave,it is easy to be realized.As an example,maximum errors less than 0.2 and 0.4 dB respectively for average gain and gain tilt were achieved over C+L band in 100-km back-pumped standard single-mode fiber (SMF) experimentally.
文摘STATCOM以快速无功控制稳定电压,但缺乏协调配合会产生交互影响。采用模态分析与相对增益矩阵(relative gain array,RGA)结合的方法进行交互影响分析,借助精确反馈线性化改进内层电流控制。建立多STATCOM系统的状态空间表达式,通过模态分析确定系统出现负阻尼振荡模式的控制器参数;结合状态空间表达式系数矩阵,求解相对增益矩阵,研究输入信号及电气距离与交互影响的关联机理;结果表明STATCOM控制器比例增益设置会引入新的局部振荡模式,引起低频功率振荡;而参考电压与电气耦合程度是负交互影响产生的重要因素。针对传统内环电流控制,利用非线性控制理论对其改进,设计输入状态反馈线性化控制器;借助线性二次型控制理论确定状态反馈矩阵,推导最优控制律,实现受控状态对期望状态的最优逼近;仿真结果表明非线性控制器能有效改善参考信号阶跃引起的功率波动,显著提高系统阻尼。
文摘阶梯式掺杂和多环式掺杂设计的掺铒光纤(EDFs)结构复杂,采用改进化学气相沉积法(MCVD)制备困难。为此,将两段铒离子分别为中心掺杂和环形掺杂的掺铒光纤级联构成四线偏振模信号光放大器。该结构放大器使中心模式信号光(LP_(01)模和LP_(02)模)和离心模式信号光(LP_(11)模和LP_(21)模)分别在中心掺杂铒光纤和环形掺杂铒光纤中获得主要增益。基于一种改进遗传算法(GA),对该放大器两段掺铒光纤的长度和铒离子掺杂半径进行优化。结果显示,仅用270m W LP_(11)模抽运光对该级联结构放大器进行抽运,四线偏振模信号光可获得20dB的平均增益,且模式相关增益(DMG)不超过3.5dB。
