Plasmonic Nanocrystal Arrays on Photonic Crystals with Tailored Optical Resonances

Juan Wang; Hai Le-The; Theodosios Karamanos; Radius N S Suryadharma; Albert van den Berg; Pepijn W H Pinkse; Carsten Rockstuhl; Lingling Shui; Jan C T Eijkel; Loes I Segerink

doi:10.1021/acsami.0c05596

Plasmonic Nanocrystal Arrays on Photonic Crystals with Tailored Optical Resonances

ACS Appl Mater Interfaces. 2020 Aug 19;12(33):37657-37669. doi: 10.1021/acsami.0c05596. Epub 2020 Aug 5.

Authors

Juan Wang^{1

2}, Hai Le-The^{2

3}, Theodosios Karamanos⁴, Radius N S Suryadharma⁵, Albert van den Berg², Pepijn W H Pinkse⁶, Carsten Rockstuhl^{4

7}, Lingling Shui¹, Jan C T Eijkel², Loes I Segerink²

Affiliations

¹ National Centre for International Research on Green Optoelectronics & South China Academy of Advanced Optoelectronics, South China Normal University, 510006 Guangzhou, China.
² BIOS Lab-on-a-Chip Group, MESA+ Institute for Nanotechnology, Technical Medical Centre & Max Planck Center for Complex Fluid Dynamics, University of Twente, 7522 NB Enschede, the Netherlands.
³ Physics of Fluids Group, MESA+ Institute for Nanotechnology & Max Planck Center for Complex Fluid Dynamics, University of Twente, 7522 NB Enschede, the Netherlands.
⁴ Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
⁵ Laser Physics and Nonlinear Optics Group, MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, the Netherlands.
⁶ Complex Photonic Systems Group, MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, the Netherlands.
⁷ Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.

Abstract

Hierarchical plasmonic-photonic microspheres (PPMs) with high controllability in their structures and optical properties have been explored toward surface-enhanced Raman spectroscopy. The PPMs consist of gold nanocrystal (AuNC) arrays (3rd-tier) anchored on a hexagonal nanopattern (2nd-tier) assembled from silica nanoparticles (SiO₂NPs) where the uniform microsphere backbone is termed the 1st-tier. The PPMs sustain both photonic stop band (PSB) properties, resulting from periodic SiO₂NP arrangements of the 2nd-tier, and a surface plasmon resonance (SPR), resulting from AuNC arrays of the 3rd-tier. Thanks to the synergistic effects of the photonic crystal (PC) structure and the AuNC array, the electromagnetic (EM) field in such a multiscale composite structure can tremendously be enhanced at certain wavelengths. These effects are demonstrated by experimentally evaluating the Raman enhancement of benzenethiol (BT) as a probe molecule and are confirmed via numerical simulations. We achieve a maximum SERS enhancement factor of up to ∼10⁸ when the resonances are tailored to coincide with the excitation wavelength by suitable structural modifications.

Keywords: localized surface plasmon resonance; photonic stop band; plasmonic−photonic microsphere; slow light effect; surface-enhanced Raman spectroscopy.