单模双折射光纤中的增益

在双折射光纤中,根据受激拉曼散射和参量放大共同作用下的斯托克斯波和反斯托克斯波所满足的耦合模方程,考虑输入泵浦波是线偏振光,推导出了与泵浦波偏振方向垂直的的斯托克斯波和反斯托克斯波的增益系数;研究了双折射色散缓变光纤中,斯托克斯波和反斯托克斯波增益随相关参量的变化关系。结果表明,与泵浦波偏振方向垂直的斯托克斯波和反斯托克斯波增益的变化趋势是完全相同和对称的;同时表明,通过改变失配系数 ,在适当的传输位置,可以实现对斯托克斯波和反斯托克斯波有选择性的输出,以达到输出频率转换的目的。     

单模双折射色散缓变光纤中拉曼散射与参量放大

根据斯托克斯波和反斯托克斯波所满足的耦合微分方程,考虑泵浦波是线偏振光,其偏振方向沿x轴,推导出了同偏振方向受激拉曼散射和参量放大同时作用下,斯托克斯波和反斯托克斯波的增益系数。研究了色散缓变光纤中增益随失配系数Δk2以及归一化距离z/L的变化关系。结果表明,当非线性系数γ=0时,增益随Δk2的变化情况在正常和反常色散区是完全对称的;而当非线性系数γ≠0时,在反常色散区增益会出现峰值,随后增益随Δk2和z/L的增加而逐渐减小。讨论了反斯托克斯波与斯托克斯波Eax/Esx的比值随失配系数Δk2的增加而快速衰减的变化特性。     

拉曼增益系数可分离光纤中的受激拉曼散射

给出了拉曼增益系数分离光纤的定义,在考虑了N个单色光之间的两两受激拉曼散射,得到了这种光纤中单向传输的N个不同的单色光之间的受激拉曼散射（SRS）稳态耦合波方程的解析解。它适用于各单色光功率任意大小、光频率分布不均匀时的一般情况。这一结果可应用于光纤通信系统、拉曼光纤放大器和拉曼光纤激光器的设计与分析。最后把解析解与数值解进行了比较,两者取得了很好的一致。     

单模光纤中超快受激拉曼散射的反斯托克斯波

由光纤中光的基本传输方程出发 ,利用慢变振幅近似 ,给出了包含反斯托克斯波的光纤超快受激拉曼散射的耦合波方程。以此为基础讨论连续、超快受激拉曼散射中泵浦波、斯托克斯和反斯托克斯波的耦合 ,分析了单模光纤相位匹配和群速匹配对光纤超快受激拉曼散射反斯托克斯波产生的影响     

双折射光纤中斯托克斯波的增益谱

根据激光脉冲在双折射光纤中传输时的混合模方程,考虑拉曼效应后,得出在受激拉曼散射和参量放大共同作用下的增益。数值模拟了当输入泵浦波沿两双折射轴450附近区域传输时,在不同色散区斯托克斯增益谱随输入功率及群速度失配等相关参数的变化关系;结果表明斯托克斯增益谱在不同色散区表现出明显不同的特性,当满足一定条件下,可利用混合模双折射光纤中传输的泵浦波分解出的脉冲序列来分离和提取T频脉冲。     

双折射光纤中斯托克斯波的增益谱

根据激光脉冲在双折射光纤中传输时的混合模方程,考虑拉曼效应后,得出在受激拉曼散射和参量放大共同作用下的增益。数值模拟了当输入泵浦波沿两双折射轴450附近区域传输时,在不同色散区斯托克斯增益谱随输入功率及群速度失配等相关参数的变化关系;结果表明斯托克斯增益谱在不同色散区表现出明显不同的特性,当满足一定条件下,可利用混合模双折射光纤中传输的泵浦波分解出的脉冲序列来分离和提取T频脉冲。     

色散位移光纤中拉曼散射与参量放大增益谱

由斯托克斯波和反斯托克斯波所满足的耦合微分方程,考虑泵浦波是线偏振光,其偏振方向沿x轴,推导出了同偏振方向受激拉曼散射和参量放大同时作用下,斯托克斯波和反斯托克斯波的增益谱.引入平行拉曼散射增益系数的洛伦兹模型,研究了色散位移光纤中斯托克斯波和反斯托克斯波的增益谱随相关参数的变化关系.结果表明,斯托克斯波与反斯托克斯波...     

低双折射光纤中拉曼增益对光偏振态的影响

利用包含拉曼增益的耦合非线性薛定谔方程, 导出了斯托克斯参量表示的含拉曼增益的杜芬方程, 通过椭圆积分求出了杜芬方程的解析解, 重点分析了光波在低双折射光纤中传播时, 拉曼增益对其偏振态演化的影响结果表明当输入功率与运动常量满足一定关系时, 拉曼增益改变了光波传输时其偏振态演化周期.     

单模光纤中Raman光放大

本文报道在单模光纤中，背向受激拉曼散射（ＢＳＲＳ）对通信光的光放大研究。所用泵浦源为声光０开关Ｎｄ￣（＋３）：ＹＡＧ激光器，工作波长１．０６４μｍ。信号源为ＩｎＧａＡｓＰ半导体激光器，工作波长１．３０μｍ。在１．３０μｍ处实现了Ｒａｍａｎ光放大，增益达１９．４ｄＢ以上，增益系数为２．３×１０￣（－１２）ｃｍ／ｗ。     

高阶色散对高双折射光纤增益谱的影响

根据参量放大和拉曼效应共同作用下的耦合波方程,在考虑高阶色散情况下,当输入泵浦波偏振方向同双折射轴成45时,通过引入拉曼增益的洛伦兹模型,研究了高双折射光纤中,参量放大和拉曼效应共同作用下的增益谱随相关参量的变化关系。结果表明：高双折射光纤中,在不同色散区,不同的输入参量（输入功率、群速度失配等）条件下,参量放大和拉曼效应共同作用下的增益谱受到高阶色散的影响,增益谱的结构、强度和谱宽产生了变化, 高阶色散对增益谱的影响不可忽略;可以利用增益谱在大群速度失配区域远离中心频率偏移的性质,提取T频率脉冲。     

Faraday rotation in a single-mode fiber with controlled birefringence

Faraday rotation within a polarization non-conserving single-mode optical fiber is used for ac magnetic field measurement. For that purpose the intrinsic fiber birefringence on the path to and from the Faraday rotation section is controlled. As control devices externally applied stress birefringence and phase retarder plates were used. With respect to magnetic field measurements on high electric potentials all control devices are placed at fiber input and output only.     

Determination of stress-induced intrinsic birefringence in a single-mode fiber by measurement of the two-dimensional stress profile

The two-dimensional (2-D) axial stress profile of a single-mode fiber is obtained with an optical tomographic measurement technique. All stress components of the fiber are calculated from a measured axial stress profile. We demonstrate that the differential group delay induced by intrinsic nonsymmetric stress as well as the induced linear birefringence between two orthogonal polarization modes can be determined with an analytic technique based on a vector perturbation method from a measured asymmetric 2-D stress distribution.     

Experimental demonstration of single-mode fiber coupling using adaptive fiber couplerExperimental demonstration of single-mode fiber coupling using adaptive fiber couplerExperimental demonstration of single-mode fiber coupling using adaptive fiber couplerExperimental demonstration of single-mode fiber coupling using adaptive fiber coupler

Coupling plane wave into a single-mode fiber （SMF） with high and steady coupling efficiency is crucial for fiber- based free-space laser systems, where random angular jitters are the main influencing factors of fiber coupling. In this paper, we verified a new adaptive-optic device named adaptive fiber coupler （AFC） which could compensate angular jitters and improve the SMF coupling efficiency in some degree. Experiments of SMF coupling under the angular jitter situation using AFC have been achieved. Stochastic parallel gradient descent （SPGD） algorithm is employed as the control strategy, of which the iteration rate is 625 Hz. In closed loop, the coupling efficiency keeps above 65% when angular errors are below 80/3tad. The compensation bandwidth is 35 Hz at sine-jitter of 15 ~rad amplitude with average coupling efficiency of above 60%. Also, experiments with simulated turbulence have been studied. The average coupling efficiency increases from 31.97% in open loop to 61.33% in closed loop, and mean square error （MSE） of coupling efficiency drops from 7.43% to 1.75%.     

Reflectometric measurement of birefringence rotation in single-mode optical fibers

We present a novel reflectometric technique for the measurement of orientation and modulus of the linear birefringence vector in single-mode optical fibers. The technique provides information also on circular birefringence, although this component, if present, appears as a rotation of the linear birefringence. A detailed theoretical analysis is reported and validated by experimental results.     

Evaluation of the residual birefringence of single-mode erbium-doped silica fibers

We present a nondestructive method that allows the spectral birefringence characterization of single-mode erbium-doped fibers within the amplification band. Using the same optical set up and the predicted polarization eigenmodes, the quality of the results has been verified. The results obtained for three commercial erbium-doped fibers with different erbium concentrations are shown. For two of them, the values measured for the elliptical birefringence shift, for different signal wavelengths, from having a dominant circular component to exhibit a dominant linear component.     

双折射光纤受激喇曼散射的研究

本文详细地研究了双折射光纤的受激喇曼散射.观测到9级斯托克斯受激喇曼谱.文中讨论和测试了阈值和频移与泵浦光偏振方向间的关系;当泵浦光偏振方向与光纤椭圆核的长轴或短轴平行时的传输损耗.并根据测得的阈值在理论上计算了各级斯托克斯线的喇曼增益系数.     

Measurement of birefringence correlation length in long, single-mode fibers

Measurements of birefringence correlation length performed on long single-mode telecommunication fibers are reported. The proposed technique relies on the statistical properties of the backscattered-field polarization, which was measured by means of a polarization-sensitive optical time-domain reflectometer. Experimental results are reported that show good agreement with the underlying theory based on stochastic differential equations.