Enhanced Performance of Single-Photon Emitter Hosted in Hexagonal Boron Nitride via Two-Photon Excitation

In the rapidly advancing field of quantum photonics, precise control of single-photon emitters (SPEs) is essential for the development of quantum technologies such as quantum computing, quantum communication, and quantum sensing. While single-photon excitation is widely used for SPEs, research on two-photon excitation is still limited, and its excitation mechanism remains unclear. In this study, we propose a mechanism for two-photon excitation involving two-photon absorption, excited-state reabsorption, radiative transitions, and nonradiative decay processes and also explore the low-temperature photophysical properties of the SPE hosted in hexagonal boron nitride under both single-photon and two-photon excitation conditions. Our findings demonstrate that under two-photon excitation, the SPE exhibits increased emission efficiency and decreased nonradiative losses, specifically manifested in narrower photoluminescence (PL) spectral line width, extended PL lifetime, and more robust PL emission, addressing key performance challenges of SPEs. Additionally, we provide insights into the underlying mechanisms that drive these improvements, offering a deeper understanding of how two-photon excitation enhances the photophysical properties of the SPE. This study highlights the potential of two-photon excitation to enhance the performance of the SPE and provides valuable insights for future quantum technology applications.