Interferometric microscale measurement of refractive index at VIS and IR wavelengths

Abstract

Determination of refractive index of micro-disks of a calcinated ($1100^{\circ }$C in air) photo-resist SZ2080${}^{\mathrm{TM}}$ 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 $\sim 6\pm 1\mu$m thickness were determined at visible and IR (2.5-13~$\mu$m) spectral ranges and where $2.2\pm 0.2$ 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.

15 pages, 6 figures, 1 supplementary page. 52 references