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Proceedings Paper

A novel monolithic beam steering high power transmitter for low cost free space optical wireless links
Author(s): Fat Kit Lau; Xin Zhao; Chyng Wen Tee; Richard Penty; Ian White; Michel Calligaro; Michel Lecomte; Olivier Parillaud; Nicolas Michel; Michel Krakowski
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Paper Abstract

A novel transmitter for directed-beam infra-red wireless that utilizes a combination of both gain-guiding and index guiding mechanism to ameliorate the shortcoming of the state-of-the-art technology is proposed and demonstrated. The 3mm long tapered laser consists of an index-guided ridge straight section and a gain-guided tapered section with a full angle of 6°. By implementing multiple contact with a sufficiently high inter-contact resistance, discrete switching between different angles can be obtained by selectively pumping current to different contact (gain-guiding effect), while fine-tuning of a given angle can be achieved by adjusting the injection current of nearby contacts (index-guiding effect). The tapered laser's metal cover is removed using focus ion beam etching technique to form three separate sections: base section as filter, left section and right section for beam steering. The device is biased by current pulses of 1μs width and 0.1% duty cycle. With a 1.6A injection current, an output power of 2W is achieved, which would be suitable to overcome large free space optical loss and facilitate the use of transmitting methods. The beam profile steered by 3.2° and -5.4° from the central lobe when injection current is limited to the left and right section respectively is measured. It is also observed that as injection current increases, the beam profile is steered towards the central position. This is because as the injection current increases, the local refractive index is decreased, thereby shifting the beam profile towards the opposite direction.

Paper Details

Date Published: 1 March 2006
PDF: 8 pages
Proc. SPIE 6105, Free-Space Laser Communication Technologies XVIII, 61050H (1 March 2006); doi: 10.1117/12.648058
Show Author Affiliations
Fat Kit Lau, Cambridge Univ. (United Kingdom)
Xin Zhao, Cambridge Univ. (United Kingdom)
Chyng Wen Tee, Cambridge Univ. (United Kingdom)
Richard Penty, Cambridge Univ. (United Kingdom)
Ian White, Cambridge Univ. (United Kingdom)
Michel Calligaro, Alcatel-Thales III-V Lab. (France)
Michel Lecomte, Alcatel-Thales III-V Lab. (France)
Olivier Parillaud, Alcatel-Thales III-V Lab. (France)
Nicolas Michel, Alcatel-Thales III-V Lab. (France)
Michel Krakowski, Alcatel-Thales III-V Lab. (France)

Published in SPIE Proceedings Vol. 6105:
Free-Space Laser Communication Technologies XVIII
G. Stephen Mecherle, Editor(s)

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