Svela Andreas Ø, Silver Jonathan M, Del Bino Leonardo, Zhang Shuangyou, Woodley Michael T M, Vanner Michael R, Del'Haye Pascal
National Physical Laboratory, Teddington, TW11 0LW, UK.
Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK.
Light Sci Appl. 2020 Dec 23;9(1):204. doi: 10.1038/s41377-020-00440-2.
As light propagates along a waveguide, a fraction of the field can be reflected by Rayleigh scatterers. In high-quality-factor whispering-gallery-mode microresonators, this intrinsic backscattering is primarily caused by either surface or bulk material imperfections. For several types of microresonator-based experiments and applications, minimal backscattering in the cavity is of critical importance, and thus, the ability to suppress backscattering is essential. We demonstrate that the introduction of an additional scatterer into the near field of a high-quality-factor microresonator can coherently suppress the amount of backscattering in the microresonator by more than 30 dB. The method relies on controlling the scatterer position such that the intrinsic and scatterer-induced backpropagating fields destructively interfere. This technique is useful in microresonator applications where backscattering is currently limiting the performance of devices, such as ring-laser gyroscopes and dual frequency combs, which both suffer from injection locking. Moreover, these findings are of interest for integrated photonic circuits in which back reflections could negatively impact the stability of laser sources or other components.
当光沿波导传播时，一部分场会被瑞利散射体反射。在高品质因数回音壁模式微谐振器中，这种固有背向散射主要是由表面或体材料缺陷引起的。对于几种基于微谐振器的实验和应用，腔内最小的背向散射至关重要，因此，抑制背向散射的能力必不可少。我们证明，在高品质因数微谐振器的近场中引入额外的散射体，可以相干地将微谐振器中的背向散射量抑制超过30 dB。该方法依赖于控制散射体的位置，使得固有和散射体诱导的反向传播场发生相消干涉。这项技术在微谐振器应用中很有用，目前在这些应用中，背向散射限制了器件的性能，如环形激光陀螺仪和双频梳，它们都受到注入锁定的影响。此外，这些发现对于集成光子电路也很有意义，在集成光子电路中，背向反射可能会对激光源或其他组件的稳定性产生负面影响。
