偏振控制器完成任意偏振态变化的最小自由度研究

Research on Least Number of Degrees of Freedom for Transformation among Arbitrary State of Polarizations

偏振控制器(PC)是处理光纤中信号偏振态(SOP)的重要器件,它是偏振模色散(PMD)自适应补偿器的重要组成部分。以两种类型的商用偏振控制器为例,理论和实验证明了转变任意输入态到庞加莱(Poincare)球上其他任何状态至少需要调整三个自由度而不是两个自由度。因此至少需要控制每一阶段的PMD补偿器中偏振控制器上的三个自由度而不是两个自由度,才能够实现完全的PMD补偿。

Automatically controlled polarization controllers （PC） are important devices for treating states of polarization （SOP） of the optical signals in fibers, which are the essential integral parts in an automatic compensator for polarization mode dispersion （PMD）. Two types of commercial available PCs are taken as examples to show theoretically and experimentally that except for the reset-free problem it is necessary to adjust at least three instead of two waveplates in order to transform any input state into any other state covering the entire Poincaré sphere. Therefore we can achieve complete PMD compensation at least using three degrees of freedom instead of two in each stage PMD compensator.