摘要： The Fano resonances observed in diverse micro and nano optical systems have received particular attention due to their numerous potential applications like sensing, switching, lasing, ?lters and robust color display, nonlinear and slow-light devices, invisibility cloaking, and so forth. For most of these applications, it is highly desirable that the asymmetric spectral line shape of Fano resonance can be controlled or modulated by some experimentally accessible parameters. In this chapter, we discuss a new concept based on polarization Mueller matrix analysis for tuning the Fano interference effect and the resulting asymmetric spectral line shape in anisotropic optical system. The approach is founded on a generalized model of anisotropic Fano resonance and exploits the differential polarization response (anisotropy) of the two interfering modes to achieve unprecedented control over Fano resonance. Illustrative results on the use of the model for tuning Fano resonance in coupled plasmonic systems are presented. In this context, the fundamentals of polarized light, the mathematical framework of Stokes-Mueller formalism and the basic polarimetry parameters encoded in Mueller matrix are discussed. The speci?cs of a novel dark ?eld Mueller matrix spectroscopy system and its use for studying the polarization response of Fano resonance in plasmonic systems is illustrated with selected examples. The chapter concludes with an outlook on the prospects of the polarization-optimized anisotropic Fano resonant systems for applications involving control and manipulation of electromagnetic waves at the nano scale.