Grin planar structures for focusing collimation and beam size control

摘要

Currently the terms GRadient INdex or GRaded INdex (GRIN) are often used to describe an inhomogeneous medium, that is, a medium in which the refractive index varies from point to point within it.~1-2 In a GrIn medium, the optical rayws follow curved trajectories, instead of straight lines as in a homogeneous medium. By an appropriate choice of the refractive index profile, a GRIn medium can have the same effect on light rays as conventional optical components, such as a prism or a lens.