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Proceedings Paper

Progressive phase conjugation and its application in reconfigurable spatial-mode extraction and conversion
Author(s): Atsushi Okamoto; Tomohiro Maeda; Yuki Hirasaki; Akihisa Tomita; Kunihiro Sato
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Paper Abstract

We develop a new technology, which is referred to as progressive phase conjugation (PPC), in which phase conjugation is electrically performed without requiring a coherent reference beam by fusion using a reference-free spatial phase detection and spatial phase modulation. This method enables remote setting of a phase detector from the signal transmitter without an additional transmission line for the reference beam. It also enables realization of high-speed and dynamic wavefront compensation owing to its open-loop architecture using the single-shot phase detection method. Therefore, the PPC is applicable to a wide range of optical communication technologies, including the reconfigurable spatial-mode extraction and conversion of mode transmission in a multi-mode fiber (MMF). In our experiment, spatial modes are generated by directing a laser beam into a MMF with a 50-micron core diameter. At the output side of the optical fiber, the phase distributions of the spatial modes are detected using the reference-free phase detector constructed by combining a spatial filtering method with holographic diversity interferometry using two CCD imagers. Then, the phase conjugate distribution of the detected phase pattern is displayed on a LCOS-type SLM. We confirm that the PPC system can extract a specific mode pattern with a considerably low crosstalk of less than 1% by displaying the corresponding phase-conjugation pattern on the SLM. In addition, we demonstrated a reconfigurable spatial-mode conversion by the phase control technology using the SLM. By applying the spatial phase modulation to an optical beam incident on the SLM, the spatial mode of the output beam is flexibly changed.

Paper Details

Date Published: 2 May 2014
PDF: 11 pages
Proc. SPIE 9130, Micro-Optics 2014, 913012 (2 May 2014); doi: 10.1117/12.2051729
Show Author Affiliations
Atsushi Okamoto, Hokkaido Univ. (Japan)
Tomohiro Maeda, Hokkaido Univ. (Japan)
Yuki Hirasaki, Hokkaido Univ. (Japan)
Akihisa Tomita, Hokkaido Univ. (Japan)
Kunihiro Sato, Hokkai-Gakuen Univ. (Japan)

Published in SPIE Proceedings Vol. 9130:
Micro-Optics 2014
Hugo Thienpont; Jürgen Mohr; Hans Zappe; Hirochika Nakajima, Editor(s)

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