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arXiv · 2507.03601

Mode-dependent Emission Thresholds and Frequencies in Metal Nanoparticles within Gain-enhanced Media

Karen Caicedo·Nicole Recalde·Milena Mora·Alonso Moreta·Maria Antonia Iatì·Onofrio M. Maragò·Melissa Infusino·Alessandro Veltri
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Abstract

We present a mode-resolved analysis of emission thresholds in metal nanoparticles embedded within an infinite gain medium, using Mie scattering theory as a rigorous framework. Focusing on the first three resonant modes, we identify the onset of emission by locating the complex zeros of the electric scattering coefficient a_n(omega), which serve as indicators of lasing conditions. Our hybrid numerical scheme-combining coarse bracketing and two-dimensional Newton refinement-enables precise determination of both the threshold gain G_th,n and the corresponding emission frequency omega_th,n across varying particle radii. The results uncover strong size-dependent behavior, with higher-order modes in larger particles exhibiting significantly reduced threshold gain. These insights elucidate the modal dynamics underlying plasmonic nanolasing and provide design guidelines for active photonic systems leveraging gain-enhanced nanoparticles.

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Karen Caicedo, Nicole Recalde, Milena Mora, Alonso Moreta, Maria Antonia Iatì, Onofrio M. Maragò, Melissa Infusino, Alessandro Veltri. 2025-07-04. Mode-dependent Emission Thresholds and Frequencies in Metal Nanoparticles within Gain-enhanced Media. https://arxiv.org/abs/2507.03601

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