title: Three-dimensionally modulated graded-index diffractive elements by thermal ion exchange in glass.
abstract: Thermal ion exchange was introduced recently [Appl. Phys. Lett. 66, 917 (1995)] as a method to generate graded refractive-index distributions that permit continuous one-dimensional phase modulation in diffractive optics. We apply enhanced diffusion-modeling techniques and a novel three-step optimization procedure to design, for the first time to our knowledge, efficient three-dimensional graded-index profiles with two-dimensional phase-modulation capability. A discrete, nonseparable inversion-symmetric signal pattern is demonstrated experimentally in which the uniformity error in the intensities of the seven signal spots is less than 5%.
authors.forename: R P
authors.initials: RP
authors.lastname: Salmio
authors.forename: H
authors.initials: H
authors.lastname: Saarikoski
authors.forename: J
authors.initials: J
authors.lastname: Saarinen
authors.forename: J
authors.initials: J
authors.lastname: Westerholm
authors.forename: J
authors.initials: J
authors.lastname: Turunen