公开(公告)号：US06380533B1

公开(公告)日：2002-04-30

申请号：US09390033

申请日：1999-09-03

申请人： Robert Meachem Jopson ,  Herwig Werner Kogelnik ,  Lynn Elizabeth Nelson

发明人： Robert Meachem Jopson ,  Herwig Werner Kogelnik ,  Lynn Elizabeth Nelson

IPC分类号： G02F101

CPC分类号： G01M11/336 ,  G02B6/105

摘要： The present invention consists of a method and apparatus for measuring first and higher order PMD vectors in optical fibers. For each first-order PMD vector determination, two distinct polarization states are sequentially injected into an optical device under test for each of a pair of frequencies &ohgr; and &ohgr;+&Dgr;&ohgr;f. A Stokes vector s1 representing the first polarization state must not be parallel or anti-parallel to a Stokes vector sa representing the second polarization state, but the relative angle between s1 and sa need not be known. The frequency interval &Dgr;&ohgr;f is large to obtain a high signal-to-noise ratio. Thus, four light beams are injected, the first at frequency &ohgr; and polarization s1, the second at frequency &ohgr; and polarization sa, the third at frequency &ohgr;+&Dgr;&ohgr;f and polarization s1, and the fourth light at frequency &ohgr;+&Dgr;&ohgr;f and polarization sa. The output polarizations of these beams are measured and four corresponding output Stokes vectors are determined. A first-order PMD vector is then calculated from the four input Stokes vectors and four output Stokes vectors. Each subsequent PMD vector determination is then made using a pair of frequencies which differs from the previous pair of frequencies by a frequency interval &Dgr;&ohgr;i which is small compared to &Dgr;&ohgr;f. Since &Dgr;&ohgr;i can be small, high spectral resolution of the PMD vector can be obtained, while still maintaining good signal-to-noise ratio provided by using a large &Dgr;&ohgr;f. The good signal-to-noise ratio and high spectral resolution of the PMD vector allow the accurate determination of second- and higher-order PMD vectors.

摘要翻译： 本发明由用于测量光纤中的第一和更高阶PMD矢量的方法和装置组成。 对于每一个一阶PMD矢量确定，两个不同的极化状态被依次注入被测光学器件中的一对ω和ω+ DELTAomegaf中的每一个。 表示第一极化状态的斯托克斯矢量s1不能与表示第二极化状态的斯托克斯矢量sa并联或反平行，而是不需要知道s1和sa之间的相对角度。 频率间隔DELTAomegaf很大，以获得较高的信噪比。 因此，注射四个光束，第一个以频率ω和极化s1，第二个以频率ω和极化sa，第三个频率ω+ DELTAomegaf和极化s1，第四个光在频率ω+ DELTAomegaf和极化sa。 测量这些光束的输出极化，并确定四个相应的输出斯托克斯矢量。 然后从四个输入斯托克斯矢量和四个输出斯托克斯矢量计算一阶PMD矢量。 然后，使用与前一对频率不同的一对频率，以与DELTAomegaf相比较小的频率区间DELTAomegai来进行每个随后的PMD矢量确定。 由于DELTAomegai可以小，可以获得PMD矢量的高光谱分辨率，同时仍然保持通过使用大型DELTAomegaf提供的良好的信噪比。 PMD矢量的良好的信噪比和高的光谱分辨率允许准确地确定二阶和更高阶的PMD矢量。

公开(公告)号：US6144450A

公开(公告)日：2000-11-07

申请号：US395238

申请日：1999-09-13

申请人： Robert Meachem Jopson ,  Herwig Werner Kogelnik ,  Lynn Elizabeth Nelson

发明人： Robert Meachem Jopson ,  Herwig Werner Kogelnik ,  Lynn Elizabeth Nelson

IPC分类号： G01J4/04 ,  G01M11/00 ,  H04B10/18 ,  G01J4/00

CPC分类号： H04B10/2569 ,  G01J4/04 ,  G01M11/333 ,  G01M11/335 ,  G01M11/336

摘要： An apparatus and method for simultaneously taking measurements that are used for determining PMD vectors. This reduces the time interval over which all measurements are taken and reduces inaccuracy caused by PMD variation during the time measurement interval. The apparatus and method may be used in conjunction with any technique for calculating PMD, such as the Poincare Sphere Technique or Jones Matrix Eigenanalysis. The apparatus simultaneously produces multiple light beams. To distinguish each light beam from the others, each beam is given a distinct modulation. All the beams are then combined and passed through the optical device under test. A polarization measuring device then measures the output polarization of the combined beam and outputs one or more composite electrical signals that describe the Stokes components of the output polarization of the combined beam and that have the same modulations present in the original combined beam. Using modulation filters having the same modulations as given to each original light beam, electrical signals may be extracted from the composite electrical signals that describe the Stokes components of the output polarization corresponding to each original light beam. Also, measurement and control of the frequency difference between light beams used for determining PMD vectors is improved by receiving light beams of two distinct frequencies using a detector that then outputs a signal having a frequency equal to the difference in frequencies of the light beams. In addition, a feedback loop is used to better control the frequency difference between two light sources. Also, a frequency shifter is used to generate two light beams separated by a specific frequency interval.

摘要翻译： 用于同时进行用于确定PMD矢量的测量的装置和方法。 这减少了所有测量的时间间隔，并减少了在时间测量间隔期间由PMD变化引起的误差。 该装置和方法可以结合用于计算PMD的任何技术，例如Poincar + E，acu e + EE球体技术或Jones Matrix特征分析。 该装置同时产生多个光束。 为了将每个光束与其他光束区分开，每个光束被给出明显的调制。 然后将所有光束组合并通过被测光学器件。 偏振测量装置然后测量组合光束的输出偏振，并且输出描述组合光束的输出偏振的斯托克斯分量并且具有存在于原始组合光束中的相同调制的一个或多个复合电信号。 使用具有与每个原始光束相同的调制的调制滤波器，可以从描述对应于每个原始光束的输出偏振的斯托克斯分量的复合电信号中提取电信号。 此外，通过使用检测器接收两个不同频率的光束来改善用于确定PMD矢量的光束之间的频差的测量和控制，该检测器然后输出具有等于光束的频率差的频率的信号。 另外，使用反馈环来更好地控制两个光源之间的频率差。 此外，使用变频器来产生由特定频率间隔分开的两个光束。