Plasmon Resonance Properties of Au, Cu and Ag Multi-layered Structures with P(VDF-TrFE)

Abstract

The theoretical modeling of the optical response of layered metal-polymer structures, which can be employed as plasmonic sensors, is carried out. The calculation of their linearly polarized light reflection is performed with the use of the well-known matrix method, which describes the electromagnetic radiation propagation through a sequence of homogeneous flat-parallel media layers. In this way, the attenuated total reflection curves of the structures containing metal films (Au, Cu, or Ag) and a polymer dielectric are obtained and analyzed. A new sensor is proposed, which will utilize the ferroelectric P(VDF-TrFE) copolymer separating metal films. This might be a perspective idea for the creation of tunable plasmonic sensors. The dependencies of the angular position of a surface plasmon resonance versus the thicknesses of structure’s layers, as well as versus the refractive index of the medium contacting to the free surface of a sensor, are considered. This makes it possible to carry out the approximate search for optimal constructive parameters of a sensor, namely, the thicknesses of metal and polymer layers, and to make conclusion about its resulting sensitivity and working range. It is found that the sensors based on a single metal film and a couple of such films separated by a polymer differ 1 ... 1.3 times in the sensitivity (single metal film demonstrates a more rapid resonant angle shift with analyte refractive index variation). It is established that the employment of Au, Cu, or Ag gives no significant changes in the sensitivity of a two-metal-layer sensor with a polymer, but the widest refractive index registration range may be expected for a Cu-based sensor.