Polarimetric dark-field spectroscopy of gold bipyramids: Measuring single particle 3D orientation

• Published in: Optics communications 2022-05, Vol.510, p.127947, Article 127947
• Main Authors: Vu, Cam Nhung, Ouzit, Zakarya, Lethiec, Clotilde, Pellarin, Michel, Maitre, Agnès, Lerouge, Frédéric, Coolen, Laurent, Laverdant, Julien
• Format: Article
• Language: English
• Subjects: Nano-optic; Nanoparticle; Optical microscopy; Optics; Physics; Plasmon resonance; Polarization
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2022.127947

We determine the 3D orientation of single gold nano-bipyramids (AuBPs) deposited on a glass substrate. These nanoparticles possess a well-defined localized surface plasmon resonance along their main axis which can be modeled as a single dipole. Orientation is deduced by polarization resolved dark-field scattering. For that purpose, a specific experiment has been built to select, analyze in polarization and resolve the scattering angles at the single nanoparticle level. Usually, the out-of-plane angle is deduced by measuring the degree of polarization (DOP) and doing numerical simulations taking into account the nature of the dipole (1D, 2D) and all experimental parameters. We compare this method with a complete measurement of the DOP as function of the collected numerical aperture (controlled by Fourier filtering). The results provide the accuracy of the polarimetric measurements. The complimentary method proposed in this article can easily be extended to more complex system. •Investigation of the determination of the 3D orientation of single gold bipyramids (AuBPs).•AuBPs possess a well-defined plasmon resonance along its long axis which acts as a dipole.•Original method based on Fourier filtering of the polarization scattering.•Evolution of the scattered polarization with the microscope objective numerical aperture allows us to give the orientation with a good confidence.