Theoretical and experimental study of temperature-dependent spectral properties of multi-layer metal-dielectric nano-film structures

We investigate theoretically and experimentally frequency-selective transmission and reflection characteristics of thin-film metal-dielectric multi-layer structures. The thin-film structures were deposited on glass substrates using a thermal evaporation technique, and their optical characteristics were studied in the visible and infrared frequency bands. A computational scheme based on a reiterative method for the calculation of reflection from a multi-layer stack is developed to model interference filters, polarization splitters and surface-plasmon sensors and also to study the effect of temperature change on the device characteristics. The temperature dependence is introduced in the model by taking into account the thermo-optic effect in the dielectrics and contributions from the phonon-electron and electron-electron scattering in metal layers. Detailed analysis of reflectance characteristics of thin-film stacks of various material compositions has been performed with the aim to estimate their temperature sensitivity, to achieve improved device performance and to design sensors and tunable filters. Keywords: thin film filters, optics of metals, surface plasmon resonance, thermal effects, thermo-optic tuning.