Plasmonic Mesostructures Prepared by Oriented Mesoporous Materials as a Template

Recent progress in top-down nanolithography now allows to fabricate plasmonic metallic structures on the scale comparable to the lightwaves.  However, it is still a challenge to fabricate structures one-order smaller than the lightwaves in a large scale.  On the other hand, bottom-up strategies, such as self-assemblies and electrochemical etching, have been studied to fabricate smaller structures as a complementary to top-down techniques.

In this study, mesoporous silica was used as a template to fabricate metallic meso-structures.  Highly-oriented mesoporous silica thin films with hexagonally-packed meso-cylinders aligned parallel to the surface were prepared on rubbing-treated silicon and silica substrates following ref.[1].  The meso-cylinders are exposed on the surface by the wet-etching treatment[2].  Oblique angle deposition of metals on the substrates results in the discrete metallic mesostructures with rod-like islands aligning along the meso-cylinders.  Figure shows the top-view image of Pt meso-grating.  We have measured optical transmission for the gold meso-gratings.  The transmission is highly polarization-sensitive, reflecting its anisotropic morphology.

Acknowledgement

We gratefully acknowledge Dr. Hirokatsu Miyata (Canon inc.) for the supply of rubbing-treated substrates.

References

1. S. Hayase et al., Langmuir 29, 7096 (2013). 2. M. Kobayashi et al., Chem. Lett. 43, 846 (2014).