title: Subwavelength-resolvable focused non-gaussian beam shaped with a binary diffractive optical element.
abstract: The diffraction-limited spot size limits the optical disk storage capacity and microscopic resolution. We describe a technique to shape a focused Gaussian beam into a superresolving beam by using a diffractive optical element fabricated by laser-assisted chemical etching. The focused shaped beam has a smaller width and a longer depth of focus than a similarly focused Gaussian beam. Using the diffraction-limited shaped beam along with threshold writing, we achieved a written pit size of less than 0.33 microm at a 695-nm laser wavelength, compared with a 0.7-microm focused Gaussian spot size (full width at e(-2) of the peak) with the same focusing lens. The energy conversion efficiency for the beam shaping was approximately 81%.
authors.affiliation: Department of Electrical and Computer Engineering, University of Miami, Coral Gables, Florida 33124, USA. mwang@miami.edu
authors.forename: M R
authors.initials: MR
authors.lastname: Wang
authors.forename: X G
authors.initials: XG
authors.lastname: Huang