Lasing and spasing with active individual core-shell plasmonic nanoresonators

TL;DR

This paper designs and optimizes active core-shell nanoresonators to enhance near-field effects, reduce spaser thresholds, and improve laser and amplifier performance using gain-metal-dielectric and gain-metal-gain compositions.

Contribution

It introduces optimized active nanoresonator designs with specific compositions for enhanced near-field, far-field, and spaser applications, highlighting the advantages of GMD and GMG structures.

Findings

GMD nanoresonators maximize local E-field for amplifiers

GMG nanoresonators optimize power-outflow for nanolasers

GMD nanoresonators achieve lower spaser thresholds

Abstract

Active core-shell nanoresonators were designed in order to achieve large near-field enhancement, large power-outflow and minimal spaser threshold in the pump E-field strength. Gain-metal-dielectric (GMD) and gain-metal-gain (GMG) nanoresonator compositions were optimized with corresponding objective functions. The average local E-field, power-outflow and extinction cross-section were mapped above the pump E-field strength and dye concentration parameter plane with the criterion that the local E-field is smaller than the damage threshold of the nanoresonator. Regions, corresponding to the maxima in the average local E-field, the highest power-outflow, or to the zero-crossing of the extinction cross-section, were selected for detailed studies. The spectral distribution of the near-field enhancement, optical cross-sections, optical responses, quantum efficiencies, as well as the polar angle distribution of the far-field radiated power and the local charge distribution of dominant modes were inspected. Based on the results the GMD nanoresonator composition is proposed to maximize local E-field in near-field amplifiers, to maximize power-outflow in far-field-emitting lasers and to minimize threshold E-field in spasers. Comparing the complete characteristics, both compositions are suitable for different operation regions, the GMG is proposed as near-field amplifier and far-field out-coupling nanolaser, whereas the GMD is unambiguously preferable to achieve optimal spaser properties.