Outstanding surface plasmon resonance performance enabled by templated oxide gratings

Abstract

Here we report a simple and scalable soft-lithography-based templating technology for fabricating Au-covered oxide (titania and zirconia) gratings by using DVDs as a structural template. The resulting plasmonic gratings simultaneously exhibit very high surface plasmon resonance (SPR) sensitivity (up to ∼940 nm per refractive index unit, nm per RIU) and figure of merit (FOM, up to 62.5). The effects of thermal annealing of the templated oxide gratings on their final plasmonic properties have been systematically investigated by both experiments and finite-difference time-domain (FDTD) simulations. Higher SPR sensitivities and slightly reduced FOMs have been observed for the annealed gratings. Additionally, the amplitude of the SPR dips gradually decreases with increasing annealing temperatures. Scanning electron microscopy and X-ray diffraction show that the annealing process enlarges the crystal domain sizes of the oxides and smoothens the final plasmonic grating surface. Systematic FDTD simulations reveal that the SPR properties (e.g., dip amplitude) of Au-covered oxide gratings are significantly affected by the deformation of the track-pitch structure caused by thermal annealing, agreeing with the experimental results. The outstanding SPR performance combined with the high thermal stability of the crystalline oxides could make the templated plasmonic gratings a promising SPR platform for many important sensing applications, such as in situ probing heterogeneous catalytic reactions under realistic conditions.

Optical Refractive Index Sensors with Plasmonic and Photonic Structures: Promising and Inconvenient Truth

“…One-dimensional (1D) metallic grating is considered as the most common grating structure to excite SPP [117][118][119][120][121][122][123], for example, optical discs were frequently employed as structural template to fabricate metallic gratings [121][122][123]. Meanwhile, the performance of an Au-covered TiO 2 gratings sensor [123] was found to be highly dependent on the thermal annealing process of the oxide grating. By tuning the annealing process, this grating-coupled SPP sensor exhibited RI sensitivity up to ∼940 nm/RIU and FoM up to 62.5 RIU −1 .…”

Resonant Subwavelength and Nano-Scale Grating Structures for Biosensing Application: A Comparative Study

“…The structure was used for RI sensing. Additional works on SPR based DVD structures can be found in [ 37 , 38 , 39 , 40 , 41 ]. Theoretical and experimental study of the SPR supported by CDs can be found in [ 42 ], biosensing application of different types of CDs is discussed in [ 43 ].…”

IP-Dip-Based SPR Structure for Refractive Index Sensing of Liquid Analytes

“…Many of these fabrication methods of gratings consist of several steps, which leads to a longer time required to structure fabrication. There have been presented interesting results of grating-coupled SPR sensors employing grating structures, mainly one-dimensional (1D) [ 26 , 27 , 28 , 29 , 30 , 31 ]. There is an effort to achieve grating-based sensors with high sensitivity and easy and cheap fabrication.…”

“…There is an effort to achieve grating-based sensors with high sensitivity and easy and cheap fabrication. For this reason, many research groups used optical discs as structural template for fabrication of metallic gratings [ 26 , 28 , 32 , 33 , 34 ]. The grating-coupled SPR sensors were used as temperature sensors [ 21 ], RI sensors [ 24 , 25 , 33 , 35 ] and as biosensors [ 10 , 18 , 19 , 32 , 36 , 37 , 38 , 39 , 40 ].…”