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AR-coated arrays of binary lenses for interconnection networks at 1.5 mu m

: Ferstl, M.; Kuhlow, B.; Pawlowski, E.

Gallagher, N.C. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Miniature and micro-optics and micromechanics : 14 - 15 July 1993, San Diego, California
Bellingham/Wash.: SPIE, 1993 (SPIE Proceedings Series 1992)
ISBN: 0-8194-1242-2
Conference "Miniature and Micro-Optics and Micromechanics" <1993, San Diego/Calif.>
Journal Article, Conference Paper
Fraunhofer HHI ()
antireflection coatings; diffraction gratings; integrated optics; lenses; optical interconnections; optical workshop techniques; optical zone plates; photolithography; sputter etching; infrared; circular apertures; antireflection coated arrays; binary lenses; interconnection networks; blazed fresnel zone lenses; quartz glass; microstructuring techniques; free space optical interconnection networks; diffraction efficiencies; kinoform profile; staircase-like profile; fabrication; repeated pattern transfer; successive reactive ion etching; focal lengths; individual elements; square apertures; diameter; wavelength; reflection losses; optical crosstalk; optical feedback effects; antireflection coated; spot-sizes; 1.52 micron; 2 mm; 200 micron; 90 percent; sio2

Arrays of two different sizes, each consisting of 16 by 16 blazed Fresnel zone lenses were fabricated in quartz glass by means of microstructuring techniques. The lenses were designed for free space optical interconnection networks operating in the IR. In order to achieve high diffraction efficiencies the kinoform profile of the microlenses was approximated by a staircase-like profile. The fabrication of the lenses involved multiple steps of repeated pattern transfer by photolithography and successive reactive ion etching. We fabricated Fresnel zone lenses with 16 levels per zone and with different focal lengths. The individual elements of the two arrays have circular and square apertures with a diameter of 2 mm and 200 mu m respectively and were designed to operate at a wavelength of 1.52 mu m. In order to reduce reflection losses, optical crosstalk as well as optical feedback effects, the Fresnel zone lens arrays were antireflection coated. The measured spot-sizes of our F/11-Fresnel zone lenses were close to the diffraction limited values and the diffraction efficiencies of the 2 mm-lenses were higher than 90%.