Metamaterial induced bound state in continuum via the self-complementary Babinet principle

Achieving high-Q resonances in photonics is crucial for devices such as sensors, filters, and emitters of electromagnetic radiation. One effective strategy for achieving such resonances involves the bound state in the continuum effect (BIC). In this paper, we demonstrate a comprehensive study of the BIC in complementary planar Babinet metamaterials in a microwave regime. A symmetry-protected BIC has been induced in a planar metamaterial due to rotation of an incident wave for small angles from normal incidence, thus releasing the high Q-factor (9.245 · 10³ in theory and 1.606 · 10³ in experiment) trapped mode at 6.625 GHz with localized components of electric dipoles and electric octopoles radiating exclusively in the plane of the metamaterial, which can be promising for planar lasers.