Method of determining the refractive index of a substance and apparatus thereof

摘要

The invention is directed to a method for determining the refractive index (n) of a substance wherein monochromatic light is conducted to a single-mode wave guide integrated into a substrate. The wave guide is brought into contact with the substance to be measured along a segment of predetermined length. In this way, the effective refractive index in this segment of the wave guide is changed. This effect is utilized for measuring the refractive index of the measured substance. The change of the effective refractive index causes a phase displacement of the light travelling through this measuring segment. This phase displacement is measured as a phase difference to a light component not influenced by the measuring substance. This measurement is preferably made interferometrically.