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Proceedings Paper

Diffractive optical element in free-space data transmission systems
Author(s): Kari J. Kataja; Pertti Paakkonen; Jari Pekka Turunen; Juha T. Rantala; Pentti Karioja
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Paper Abstract

We demonstrate the design and performance of an array-type diffractive element, which is capable of modifying the beam of a matrix-type vertical-cavity-surface-emitting-laser (VCSEL). The diffractive element was designed for line-of-sight or non- line-of-sight multi-beam transmitter with a maximum illuminating angle of 50 degrees. To demonstrate wide-angle illumination, a single element providing the largest 50-degree illumination angle was designed and fabricated. The element was designed in the paraxial domain by the geometrical map- transformation method. Beam deflection to the desired angle was performed by Lohmann's detour-phase principle. The local diffraction efficiency of the binary element was analyzed by rigorous electromagnetic diffraction theory. The element was fabricated as a pixel-array, in which the pixel size was 200 nm X 200 nm and the size of the element was 250 micrometer X 250 micrometer. The performance of the element was characterized by measuring the irradiance at the observation plane by a CCD-camera, and by measuring the diffraction efficiencies of three diffraction orders with a separate detector. The measured diffraction efficiency and the irradiance distribution of the element for the -1st order was 27.5%, which was in fair agreement with the calculated 23.9% efficiency after taking the real properties of the VCSEL beam into consideration.

Paper Details

Date Published: 10 March 2000
PDF: 8 pages
Proc. SPIE 3951, Diffractive/Holographic Technologies and Spatial Light Modulators VII, (10 March 2000); doi: 10.1117/12.379355
Show Author Affiliations
Kari J. Kataja, VTT Electronics and Univ. of Oulu (Finland)
Pertti Paakkonen, Univ. of Joensuu (Finland)
Jari Pekka Turunen, Univ. of Joensuu (Finland)
Juha T. Rantala, VTT Electronics and Infotech Oulu (Finland)
Pentti Karioja, VTT Electronics and Infotech Oulu (Finland)

Published in SPIE Proceedings Vol. 3951:
Diffractive/Holographic Technologies and Spatial Light Modulators VII
Ivan Cindrich; Sing H. Lee; Richard L. Sutherland, Editor(s)

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