Excitation of surface plasmon polariton modes with multiple nitrogen vacancy centers in single nanodiamonds

TL;DR

This study demonstrates the coupling of multiple nitrogen-vacancy centers in nanodiamonds to surface plasmon polariton modes on metal surfaces and V-grooves, enhancing fluorescence and enabling potential quantum sensing applications.

Contribution

It introduces experimental methods for coupling multiple NV centers in nanodiamonds to SPP modes on silver and gold structures, advancing quantum sensing and plasmonic device integration.

Findings

Fluorescence spectra differences observed between source and scattering NDs.

Changes in NV lifetime when inside V-grooves.

Fluorescence emission from V-groove terminations confirms coupling.

Abstract

Nitrogen-vacancy (NV) centers in diamonds are interesting due to their remarkable characteristics that are well suited to applications in quantum-information processing and magnetic field sensing, as well as representing stable fluorescent sources. Multiple NV centers in nanodiamonds (NDs) are especially useful as biological fluorophores due to their chemical neutrality, brightness and room-temperature photostability. Furthermore, NDs containing multiple NV centers also have potential in high-precision magnetic field and temperature sensing. Coupling NV centers to propagating surface plasmon polariton (SPP) modes gives a base for lab-on-a-chip sensing devices, allows enhanced fluorescence emission and collection which can further enhance the precision of NV-based sensors. Here, we investigate coupling of multiple NV centers in individual NDs to the SPP modes supported by silver surfaces protected by thin dielectric layers and by gold V-grooves (VGs) produced via the self-terminated silicon etching. In the first case, we concentrate on monitoring differences in fluorescence spectra obtained from a source ND, which is illuminated by a pump laser, and from a scattering ND illuminated only by the fluorescence-excited SPP radiation. In the second case, we observe changes in the average NV lifetime when the same ND is characterized outside and inside a VG. Fluorescence emission from the VG terminations is also observed, which confirms the NV coupling to the VG-supported SPP modes.