Cosserat gyro-birefringence. An introduction to nonsymmetrical photoelasticity

Mechanical couple stresses modify at a microscopic level optical properties of some materials so they can display gyro-birefringence phenomena. The Optical Cosserat medium is defined and optical rotation tensor relative to couple stress is introduced. The generalized tensor of the dielectric permittivity is written for the Cosserat medium. Split of the plane-polarized light wave on passing through the Cosserat medium is shown and rotation of the azimuth of polarization is expressed by components of the couple stress tensor.