Interferometric microscale measurement of refractive index at VIS and IR wavelengths

Abstract

Determination of refractive index of micro-disks of a calcinated (1100^\circ1100∘C in air) photo-resist SZ2080^\mathrm{TM}TM was carried out using transmission and reflection spectroscopy. Interference fringes at specific wavenumbers/wavelengths were selected for determination of the optical thickness, hence, the refractive index when the thickness of micro-disks was measured by scanning electron microscopy (SEM). Refractive index of disks of \sim 6± 1~\mu∼6±1μm thickness were determined at visible and IR (2.5-13~\muμm) spectral ranges and where 2.2± 0.22.2±0.2 at visible and IR wavelengths. Peculiarities of optical characterisation of micro-optical structures are discussed in view of possible uncertainties in the definition of geometric parameters, shape and mass density redistribution.