Comparison Study of Optical Sensing Property of Gratings with and without Lamellae Layers

Abstract

Local plasmatic resonance existing around nanoscale metallic structures is closely related to the refractive index of the surrounding media. Gold Lamellae layers embedded in gratings are ideal to populate the plasmatic resonances locally with much higher concentration than the simple gratings, leading to enhanced sensitivity to the testing materials. Based on our earlier success in replicating dielectric lamellae layers, this paper reports our further work in converting the dielectric lamellae layers into gold ones and the study of their optical property as refractive index sensors. To prove the local surface plasmatic resonance be responsible for absorbing the light, the gratings without the lamellae layer were also tested for comparison. Both numerical simulation using the finite difference time domain method and optical measurements have demonstrated the enhanced sensitivity by the gratings with lamellae layers, although structural optimization is still needed. With the further improvement in both structural configuration, material and nanofabrication technique, it is believed that the proposed lamellae layers should be a promising candidate for highly sensitive environmental sensors.