Optimized optical cavity for maximal enhancement of terahertz spintronic emission

Abstract

Spintronic terahertz emitters are recently developed broadband sources for THz applications based on the ultrafast spin-diffusion in ferromagnetic/nonmagnetic ultra-thin multilayers. We present the enhancement of the terahertz emission using the integration of an optimized SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> /TiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> photonic crystal combined with our previously reported original architecture of a spintronic emitter with induced magnetic anisotropy. Layer thicknesses of the optical cavity are designed for maximal infrared pump absorption in the ferromagnetic layers to obtain intense terahertz emission. The improvement of the efficiency by factor four of terahertz emission is demonstrated compared to a spintronic emitter integrated with Bragg mirror and standard spintronic emitter.