Abstract
The active control of upconversion polarization in lanthanide-doped nanocrystals through plasmon-photon coupling enables ultracompact nonlinear photonic devices for polarization-encoded optical communication and information processing. However, current plasmonic nanostructures used for this purpose suffer from limited tunability and insufficient sensitivity to polarization, making effective control challenging. Here, we introduce an upconversion plasmonphore platform that overcomes the limitations of isotropic upconversion nanocrystals by utilizing anisotropic gap-plasmon-mode-supported metasurfaces. This platform allows the precise control of plasmon-enhanced excitation polarization and plasmon-coupled emission. When excited with linearly polarized light, the hybrid nanoplatform can switch between four upconversion polarization states, enabling multi-level photonic outputs in parallel or orthogonal configurations. We also demonstrate an information multiplexing scheme using this platform. Our numerical and experimental results not only shed light on nonlinear light-matter interactions and luminescence anisotropy at the nanoscale but also facilitate the development of novel nonlinear polaritonic nanodevices for polarization-based integrated photonics.
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•Polarization-controlled upconversion by anisotropic plasmon engineering•Selective polarization modification of excited and radiative dynamics•Programmable nonlinear optical systems with multiple polarization levels
The control of light polarization is essential for diverse applications, such as information encoding, display technology, and biological sensing. Lanthanide-doped upconversion nanoparticles show promise as quantum light sources for accurate information identification due to their characteristic spectroscopic features. In this work, we demonstrate the precise control of the polarization of isotropic nanoparticles by coupling them with anisotropic gap plasmon modes. By controlling the incident and detection polarization angles in the far field, the hybrid nanoplatform can switch between four upconversion polarization states, enabling parallel or orthogonal photonic outputs. This capability opens up possibilities for programmable nonlinear optical systems with multiple polarization levels. Our investigations provide valuable insights into the design principles for advanced nonlinear quantum systems, offering tailored frequency and polarization behavior at the nanoscale.
We introduce a platform for upconversion plasmonics that overcomes the limitations of isotropic upconversion nanocrystals by utilizing anisotropic metasurfaces supported by a gap plasmon mode. This platform allows the precise control of plasmon-enhanced excitation polarization and plasmon-coupled emission. When excited with linearly polarized light, the hybrid nanoplatform can toggle between four upconversion polarization states, enabling the generation of multi-level photonic outputs in parallel or orthogonal configurations. Our numerical and experimental results shed light on nonlinear light-matter interactions and luminescence anisotropy at the nanoscale.