Measurement of the Jones Matrix of an Optical System by Return-path Null Ellipsometry

Abstract

A return-path null ellipsometer (RPNE), whose polarizing/analysing optics (PAO) consist of a linear polarizer and a linear quarter-wave retarder (QWR), provides only two independent null measurements. The two nulls are sufficient to determine a normalized Jones matrix that is defined by one or two complex parameters. This covers a large number of important cases of reciprocal optical systems (samples) that have diagonal, antisymmetric or symmetric Jones matrices. To determine an arbitrary normalized Jones matrix of three independent complex parameters, one or more additional null measurements can be made in the presence of a second auxiliary QWR placed between the sample and return mirror. For a non-reciprocal optical system with the same Jones matrix for forward and reverse propagation, the square of the Jones matrix can be measured using RPNE by adding a non-reciprocal element (e.g. a Faraday rotator) to the PAO.