Enhanced infrared absorption by Rhodamine 6G dye on diffraction grating of the Au/Pd thin film

Abstract

Today, IR nanosensors have many applications in science and technology. Extraordinary optical transmission (EOT) through an array of ordered subwave holes in a thin metallic film is used to create some kind of high-sensitivity sensor. In this work, we performed micro-hole arrays fabrication in thin film Au/Pd (80 / 20 %) by ablation technology using femtosecond laser pulses Micro-holes with diameters d ~ 2÷3 pm and periods p ~ 5 pm were produced. We studied the enhanced infrared absorption by Rhodamine 6G (R6G) dye on diffraction grating of the Au/Pd thin film. A deposited rhodamine layer exhibits infrared absorption, which is enhanced in the range of 1400-1600 cm^-1 when approaching the edge of the first band gap with the maximum gain of about 10.