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Optical Engineering

Improvement of contrast ratio in quadriphase-shift-keying optical label recognition with passive optical waveguide circuit
Author(s): Hiroki Kishikawa; Yoshihiro Makimoto; Kensuke Inoshita; Sanae Igarashi; Nobuo Goto; Shin-ichiro Yanagiya
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Paper Abstract

In photonic label routing networks, recognition of optical labels is one of the key functions. We have proposed waveguide-type optical circuits for recognition of optical labels encoded in quadriphase-shift-keying (QPSK) form. A basic device for the circuits consists of a 3-dB directional coupler, two Y-branches, and an asymmetric X-junction coupler. We employed a scheme of complete interference of optical waves between each coded pulse and a reference pulse in our previously reported paper. The contrast ratio of the output at the destination output port to the outputs at the other ports was reported to decrease to 1.6, 1.28, and 1.13 for two-, three-, and four-stage circuits for recognition of 16, 64, and 256 QPSK labels, respectively. We find optimum circuits with improved contrast ratio of 1.8, 1.6, and 1.47 for 16, 64, and 256 labels, respectively. The recognition operation with the improved circuits is numerically confirmed using the beam propagation method. Noise tolerance of the proposed circuits is also clarified by numerical simulation. The improved circuits are optimum from the viewpoint of efficient use of optical power and noise tolerance.

Paper Details

Date Published: 31 May 2016
PDF: 12 pages
Opt. Eng. 55(5) 057104 doi: 10.1117/1.OE.55.5.057104
Published in: Optical Engineering Volume 55, Issue 5
Show Author Affiliations
Hiroki Kishikawa, The Univ. of Tokushima (Japan)
Yoshihiro Makimoto, The Univ. of Tokushima (Japan)
Kensuke Inoshita, The Univ. of Tokushima (Japan)
Sanae Igarashi, The Univ. of Tokushima (Japan)
Nobuo Goto, The Univ. of Tokushima (Japan)
Shin-ichiro Yanagiya, The Univ. of Tokushima (Japan)

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