Light-matter interaction in photonic crystal nanocavities

Summary form only given. Due to their small mode volume, photonic crystal nanocavities are an ideal tool to study enhanced light-matter interactions. As the cavity resonance and Q-factor will change under the influence of objects brought into its evanescent field, the cavity can be used to measure the polarizability of those objects. We show for the first time that a photonic crystal nanocavities, can even be used to measure the magnetic polarizability of a metal nanoring. This is the first measurement of magnetic light-matter interaction at optical frequencies.