Tailoring polaritonic dephasing in magnetic photonic crystals

Abstract

A magnetic mode and an underlying waveguide mode can form a so-called magnetic plasmon polariton. We study its femtosecond dynamics [1, 2], where the magnetic field is confined in the waveguide. We fabricated a magnetic photonic crystal [3] using electron-beam lithography and a lift-off process, consisting of gold cut wire pairs separated by a magnesium fluoride spacer on a HfO2-waveguide (see inset (d)). With the correct grating period we can couple the polaritonic and the photonic system. In order to tune the coupling strength and to tailor the dephasing, we fabricated a sample with varied grating period to shift the magnetic resonance in and out of our laser excitation. The exact resonance of the magnetic photonic crystal with respect to the laser spectra is shown in Fig. 1(a)-(c) (thin red line).