Magneto-optical Kerr effect and photonic band gap in cobalt nano-disc array

Abstract

In this paper, we report our experimental investigation on two-dimensional (2-D) magneto-photonic crystals (MPCs) by using high-precision magneto-optical Kerr effect (MOKE) measurement. Our 2-D MPC is in the form of a periodic triangular array of cobalt (Co) circular nano-discs on a silicon (Si) substrate. Preliminary longitudinal MOKE measurement reveals a hysteresis loop that suggests a saturated Kerr rotation of ≈ 0.05°. We numerically investigate the potential photonic band gap (PBG) phenomenon of a triangular nano-disc array with the Co real refractive index = 2.26 by using 2-D finite-different time-domain (FDTD) method. We observe relatively wide TM-polarization (E-field 1 substrate) band gaps in the 1550-nm telecommunication wavelengths: 500 nm in the Γ-M direction whereas 400 nm in the Γ-K direction.