The study of birefringent homogenous medium with geometric phase
  The property of linear and circular birefringence at each point of the optical medium has been evaluated here from differential matrix $N$ using the Jones calculus.This matrix lies on the OAM sphere for $l=1$ orbital angular momentum.The geometric phase is developed by twisting the medium uniformly about the direction of propagation of the light ray. The circular birefringence of the medium,is visualized through the solid angle and the angular twist per unit thickness of the medium, $k$,that is equivalent to the topological charge of the optical element. 
Dipti Banerjee
physics.optics