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International Electrical Engineering Congress (iEECON)

Effect of Nanopillar Sidewall Angle on Photon Collection Efficiency in Diamond Emitters

Preeti Ovartchaiyapong

Published Mar 5, 2025• 0 citations
Publisher

Abstract

Nitrogen-vacancy (NV) centers in diamond are valuable for quantum computing, sensing, and secure communication due to their stable room-temperature operation. However, efficient photon collection is limited by diamond’s high refractive index, leading to significant internal reflection. This work investigates how varying the sidewall angle of diamond nanopillars can affect photon collection efficiency, using finite element method (FEM) simulations. Results indicate that nanopillars with sidewall angles near 90 degrees optimize collection for x-oriented dipoles, while y-oriented dipoles perform best around 86 degrees. NV center depth within the nanopillar also affects efficiency, with certain depths favoring specific angles. Our findings show that angled sidewalls can enhance photon collection while also provide greater structural stability compared to vertical designs, offering a practical pathway to improve NV center-based quantum devices.

DOI
10.1109/ieecon64081.2025.10987601

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We present a novel design of optical nanostructure for efficient light extraction from nitrogen vacancy (NV) center in diamond. Numerical simulations of the optimal structure exhibit significant collection efficiency along with a stable radiation profile. We achieved a photon collection efficiency of 70% even with a lower numerical aperture of 0.5. Two different approaches (simple cone and encapsulated cone) have been adopted to reach a high geometrical tolerance without affecting much to the efficiency and emission profile. Besides that, our structure adds an extra benefit in terms of emission enhancement near zero phonon line (ZPL) region of NV spectra. Overall, this cone shaped diamond structure provides a robust, highly efficient and directional emission which can be integrated with a quantum optical network for various applications.
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Nitrogen-vacancy (NV) centers in diamond have emerged in recent years as a leading platform for high-sensitivity microwave sensing, due to their spin-dependent optical response and stability at room temperature. In this work, we propose a hybrid modeling approach that combines Lindblad-based quantum dynamics with classical electromagnetic simulations to study and improve the emission behavior of NV centers under coherent optical excitation. A three-level open quantum system is used to describe the NV dynamics under green laser excitation, with a Rabi frequency ofΩ12=7.24Γ13\Omega_{12}=7.24\Gamma_{13}Ω12​=7.24Γ13​. To enhance photon extraction, we design a dielectric bullseye nanoantenna that reshapes the emission pattern and increases the radiated power by over 100 times. This combined approach offers a practical route for optimizing NV-based emitters in microwave quantum sensing for telecommunications application.
Nitrogen vacancy (NV) centers in nanodiamonds have garnered significant interest for their applications in quantum sensing, imaging, and information processing. However, the ensemble brightness of NV centers is limited by surface-related effects, including surface defects and charge fluctuations, which can lead to unstable emission characteristics. This study aims to enhance the ensemble brightness and stability of NV centers in nanodiamonds through optimized surface composition. We investigate the impact of different surface modifications and treatments on the emission properties of NV centers. By carefully engineering the surface composition, we demonstrate a significant improvement in ensemble brightness while maintaining stable emission characteristics. The optimized surface composition minimizes surface defects and charge fluctuations, leading to enhanced photon collection efficiency and prolonged photon emission lifetimes. These findings provide valuable insights for the design and development of nanodiamond-based systems with improved quantum emission properties.