Plasmonic nanoantennas array based on T-shape dichroic metastructures for surface-enhanced infrared absorption applications

The metasurface based on gold T-shape nanoantennas array is fabricated and the absorbance spectrum is demonstrated for different orientation of linear polarized light. It is obtained that the plasmonic resonance of absorbance spectrum strongly depends on the polarization orientation. The effect of enhancement of IR vibrational spectrum of a thin layer of organic semiconductor covering the suggested metasurface is studied. For the series of samples of different layer thicknesses (from 5 to 130 nm) the strong effect of SEIRA (surface-enhanced infrared absorption) is demonstrated. Moreover, the special geometry of T-shape structure considered the analyte vibration levels makes it possible to control the light-matter interaction strength by changing orientation of light polarization. The SEIRA effect is discussed in terms of Fano resonance.