Gradient-index (GRIN) media offer advantages over thin optical elements for beam shaping of strongly diffracting fields. A numerical GRIN design method is presented, where diffraction effects are considered in solving for the refractive index profile. The index profile is found by specifying a desired beam transformation throughout the GRIN volume and solving a series of phase retrieval problems. A Gaussian to flat-top beam shaper and a coherent beam combiner are shown as examples. Reduced beam distortion is demonstrated in comparison to a purely geometric design method.
Bibliographical noteFunding Information:
The authors acknowledge financial support from Defense Advanced Research Projects Agency (DARPA) (HQ0034-14-D-0001) and the United States Department of Defense Air Force (FA9550-14-1-0382). We gratefully acknowledge Di Lin for providing his geometric GRIN design code.
©2016 Optical Society of America.