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.