We discuss a promising method to assess the refractive index profile of vertically aligned disordered Silicon nanowirearrays. The aberration-free micro-reflectivity set-up equipped with an in-situ optical microscope is designed tomeasure the reflectivity from 4μm~2 area of the nanowires. The spatial- and polarization-dependent reflectivity valuesalong the nanowire length is used to estimate the refractive index profile. The transfer matrix method involving theestimated refractive index profiles is employed to corroborate the measured reflectivity values. The disordered Siliconnanowires with gradient refractive index profile can suppress 96 % reflectivity irrespective of direction, wavelength,and polarization which make them a potential candidate for photon management applications.
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