Dissipative modes, Purcell factors and directional beta factors in gold bowtie nanoantenna structures

TL;DR

This paper provides a comprehensive quasinormal mode analysis of gold bowtie nanoantennas, revealing how substrate effects and multi-mode behavior influence emission properties crucial for quantum and sensing applications.

Contribution

It introduces a detailed modal analysis of gold bowtie nanoantennas, emphasizing substrate effects, multi-mode behavior, and their impact on emission and quenching.

Findings

Directional beta factor dominated by substrate emission

Gap size and substrate significantly affect Purcell factors

Multi-mode behavior influences emission efficiency

Abstract

We present a detailed quasinormal mode analysis of gold bowtie nanoantennas, and highlight the unusual role of the substrate and the onset of multi-mode behaviour. In particular, we show and explain why the directional radiatiave beta factor is completely dominated by emission into the substrate, and explain how the beta factors and quenching depend on the underlying mode properties. We also quantitatively explain the generalized Purcell factors and explore the role of gap size and substrate in detail. These rich modal features are essential to understand for future applications such as sensing, lasing, and quantum information processing, for example in the design of efficient single photon emitters.