*Article* **Role of Geometric Shape in Chiral Optics**

#### **Philipp Gutsche 1,2,\*, Xavier Garcia-Santiago 3, Philipp-Immanuel Schneider 4, Kevin M. McPeak 5, Manuel Nieto-Vesperinas 6 and Sven Burger 2,4**


Received: 11 November 2019; Accepted: 8 January 2020; Published: 13 January 2020

**Abstract:** The distinction of chiral and mirror symmetric objects is straightforward from a geometrical point of view. Since the biological as well as the optical activity of molecules strongly depend on their handedness, chirality has recently attracted high interest in the field of nano-optics. Various aspects of associated phenomena including the influences of internal and external degrees of freedom on the optical response have been discussed. Here, we propose a constructive method to evaluate the possibility of observing any chiral response from an optical scatterer. Based on solely the *T*-matrix of one enantiomer, planes of minimal chiral response are located and compared to geometric mirror planes. This provides insights into the relation of geometric and optical properties and enables identifying the potential of chiral scatterers for nano-optical experiments.

**Keywords:** optical chirality; mirror symmetry; helicity; optical scatterer
