All-fiber ellipsometer for nanoscale dielectric coatings

Measuring the refractive index and the thickness of thin films (films with a thickness from less than a nanometer to several microns) is essential to characterize them and improve the performance of sensors and devices that employ thin films. The most established method to simultaneously determine both parameters, with a wide range of available commercial solutions, is ellipsometry. However, this technique does not directly measure the thickness and the refractive index, but calculates them based on optical measurements and an optical model of the thin film material that must be known in advance.