The Fano resonance has been a familiar and important feature in atomic and molecular physics for more than half a century. Typically, the combination of a discrete state with one or more continua results in an asymmetric peak in the ionization spectrum. The peak-shape, called the Fano profile, can be expressed by a simple formula derived by Fano in 1935. However, the interpretation of its characteristic parameter q, which represents the asymmetry of the peak in the formula, is not necessarily intuitively transparent. The Fano resonance is not necessarily a quantum effect, but it is a manifestation of a certain physical mechanism in various systems, both quantum and classical. Through the derivation of q from the known classical pictures with the classical coupled oscillator, we interpret the q value with a geometrical view. And further, we introduce a complex valued q parameter for the description of the resonance with a damped oscillator.

半个多世纪以来，法诺共振一直是原子和分子物理学中熟悉且重要的特征。通常，离散状态与一个或多个连续状态的组合会导致电离谱中出现不对称峰。峰形，称为 Fano profile，可以用 Fano 在 1935 年推导出的一个简单公式表示。但是，其特征参数q的解释，在公式中代表峰的不对称性，并不一定直观透明。法诺共振不一定是量子效应，但它是各种系统中某种物理机制的表现，无论是量子还是经典。通过q的推导从具有经典耦合振荡器的已知经典图片中，我们用几何视图解释q值。此外，我们引入了一个复值q参数来描述阻尼振荡器的共振。