Pyramidal Hyperbolic Metasurfaces Enhance Spontaneous Emission of Nitrogen‐Vacancy Centers in Nanodiamond

Abstract

and spin-selective optical transitions of NV centers form the basis of optically detected magnetic resonance and have fostered a plethora of interest in developing quantum biosensing methods, as exemplified by the nanoscale magnetometry [1e,2a] and spinenhanced ultrasensitive diagnostics. [1a-c] Yet, the achievable sensitivity and temporal resolution are compromised by inefficient photon generation and extraction from excited NV centers owing to their long radiative lifetime, which ranges from 10 to 30 ns depending on the size and refractive index of nanodiamonds.Boosting the efficiency of photon generation hinges on accelerating the spontaneous emission of NV centers. [2c,3] For conventional quantum emitters such as semiconductor quantum dots and organic dyes, their transition dynamics can be modified by the Purcell effect, which is linearly dependent on the quality factor but inversely scales with the mode volume of an optical cavity. [3b,c,4] Owing to the high-Q cavity mode of a dielectric resonator and the subwavelength mode volume of a plasmonic nanocavity, they are both well suited to provide a significant Purcell enhancement to accelerate the transition dynamics of quantum emitters, provided that the optical cavity is tuned to be in resonance with the emission spectrum of quantum emitters. However, as an optical cavity usually supports a much narrower spectral linewidth than the broadband emission spectrum of NV centers, it proves less Nitrogen-vacancy (NV) centers in nanodiamond hold great promise for creating superior biological labels and quantum sensing methods. Yet, inefficient photon generation and extraction from excited NV centers restrict the achievable sensitivity and temporal resolution. Herein, an entirely complementary route featuring pyramidal hyperbolic metasurface is reported to modify the spontaneous emission of NV centers. Fabricated using nanosphere lithography, the metasurface consists of alternatively stacked silica-silver thin films configured in a pyramidal fashion, and supports both spectrally broadband Purcell enhancement and spatially extended intense local fields owing to the hyperbolic dispersion and plasmonic coupling. The enhanced photophysical properties are manifested as a simultaneous amplification to the spontaneous decay rate and emission intensity of NV centers. It is envisioned that the reported pyramidal metasurface can serve as a versatile platform for creating chip-based ultrafast single-photon sources and spin-enhanced quantum biosensing strategies, as well as aid in further fundamental understanding of photoexcited species in condensed phases.

Metasurfaces toward Optical Manipulation Technologies for Quantum Precision Measurement

“…proposed a fully complementary route to modify the spontaneous emission from the NV center featuring a pyramidal metasurface. [ 211 ] The NV centers in nanodiamonds were measured by fluorescence lifetime imaging microscopyon the fabricated pyramidal cell surface, and numerically obtained results have been validated that the pyramidal metasurface provides a broadband enhancement mechanism in both spectral and spatial domains. The introduction of the metasurface paves the way for the realization of chip‐based ultrafast photonic devices and the development of spin‐enhanced quantum optical sensing strategies.…”

Plasmon-enhanced fluorescence for biophotonics and bio-analytical applications

“…(Gao et al, 2023;Lu et al, 2023;Rippa et al, 2024). The present technique of specific RNA quantification involves complementary base pairing between a The fluorescence intensity images of NV centres measured on the pyramidal metasurface, the Ag nanopyramid, and the quartz substrate, respectively, in a dimension of ≈14 μm × 14 µm with an excitation wavelength of 532 nm (Zheng et al, 2023).…”

Enhancing the Emission Rate of the Inherent Silicon‐Vacancy Center Using Optimized Multipolar Moments in a Silicon Carbide Metasurface

“…[ 31 ] Apart from these passive applications of metasurfaces, recently, metasurface with hyperbolic dispersion is proposed as a viable platform to control the quantum emitter emission properties. [ 32 ] Thus, by modulating the interplay between the excited multipoles in metasurfaces that results in strong localized fields, significant emission enhancement for quantum emitters can be achieved due to the increased interaction with the local density of states (LDOS). However, it has been observed that metasurfaces coupled with single quantum emitters can boost the emission rate and directionality of the emitted single photon, which opens new avenues of metaphotonics in quantum technologies.…”