Moroney N, Del Bino L, Zhang S, Woodley M T M, Hill L, Wildi T, Wittwer V J, Südmeyer T, Oppo G-L, Vanner M R, Brasch V, Herr T, Del'Haye P
Max Planck Institute for the Science of Light, 91058, Erlangen, Germany.
QOLS, Blackett Laboratory, Imperial College London, SW7 2AZ, London, UK.
Nat Commun. 2022 Jan 19;13(1):398. doi: 10.1038/s41467-021-27933-x.
Kerr-effect-induced changes of the polarization state of light are well known in pulsed laser systems. An example is nonlinear polarization rotation, which is critical to the operation of many types of mode-locked lasers. Here, we demonstrate that the Kerr effect in a high-finesse Fabry-Pérot resonator can be utilized to control the polarization of a continuous wave laser. It is shown that a linearly-polarized input field is converted into a left- or right-circularly-polarized field, controlled via the optical power. The observations are explained by Kerr-nonlinearity induced symmetry breaking, which splits the resonance frequencies of degenerate modes with opposite polarization handedness in an otherwise symmetric resonator. The all-optical polarization control is demonstrated at threshold powers down to 7 mW. The physical principle of such Kerr effect-based polarization controllers is generic to high-Q Kerr-nonlinear resonators and could also be implemented in photonic integrated circuits. Beyond polarization control, the spontaneous symmetry breaking of polarization states could be used for polarization filters or highly sensitive polarization sensors when operating close to the symmetry-breaking point.
克尔效应引起的光偏振态变化在脉冲激光系统中是众所周知的。一个例子是非线性偏振旋转，它对许多类型的锁模激光器的运行至关重要。在此，我们证明了高精细度法布里 - 珀罗谐振器中的克尔效应可用于控制连续波激光器的偏振。结果表明，通过光功率控制，线性偏振输入场可转换为左旋或右旋圆偏振场。这些观察结果可通过克尔非线性引起的对称性破缺来解释，这种对称性破缺在原本对称的谐振器中分裂了具有相反偏振手性的简并模式的共振频率。在低至7 mW的阈值功率下展示了全光偏振控制。这种基于克尔效应的偏振控制器的物理原理对于高Q克尔非线性谐振器是通用的，并且也可以在光子集成电路中实现。除了偏振控制之外，当在接近对称性破缺点的条件下运行时，偏振态的自发对称性破缺可用于偏振滤波器或高灵敏度偏振传感器。
