Loss circumvention and plasmonic lasing in arrays of magnetic nanodots

Abstract

The results compiled in this dissertation range from basic research on magnetoplasmonic to applications where magneto-optics and plasmonics are brought together to bring out the best of both fields. Four main topics were explored: the excitation of surface plasmon in arrays of Co/Pt nanodots, demagnetization and magnetic switching in magnetoplasmonic systems triggered by femtosecond pulses, loss circumvention in magnetoplasmonic systems, and lasing in magnetoplasmonic nanocavities.

The systematic study of Co/Pt nanodot arrays provides a comprehensive guide to the excitation of surface lattice resonances in this relevant material system as well as a detailed explanation of the origin of their optical and magneto-optical response. Additionally, the exploitation of surface plasmon excitations in ultrafast demagnetization and laser-induced magnetic switching is discussed for Ni nanodot arrays. Surface lattice resonances in this system enhance the absorption of femtosecond laser pulses, rendering more efficient heating of the Ni nanodots. The problem of optical losses in metallic magnetoplasmonic systems is also examined. The development of a new loss circumvention method based on arrays of magnetic nanodots and the excitation of surface plasmon polaritons at a metal/dielectric interface enabled the excitation of high-quality factorplasmonic resonances comparable to those obtained in pure noble metal systems. These narrow resonances do spectrally tailor and strongly enhance the magneto-optical response of the magnetic nanodots. Lastly, the excitation of narrow plasmonic resonances in arrays of Co/Pt nanodots overlaid with an organic gain medium provides efficient nanoscale lasing. It is important to note that active magnetic field control of the lasing intensity is demonstrated for the first time in this system. The effect is ascribed to magnetic circular dichroism in the Co/Pt nanodots.