GRATING LENSES FOR OPTICAL BRANCHING

Grating lenses for optical branching were designed by introducing a ph ase-modulation function. The lenses have the dual functions of focusin g and branching. The phase-modulation function was optimized to balanc e the optical intensity values for the required branchings and to supp ress those for undesirable branchings. Phase-modulated grating lenses, with three and five branchings, were fabricated by using a computer a nd an electron-beam exposure system. The focusing and branching charac teristics obtained by these lenses show excellent agreement with the t heoretically predicted profiles.