Materials, Photonic Devices, and Sensors

Improvement of contrast ratio in quadriphase-shift-keying optical label recognition with passive optical waveguide circuit

[+] Author Affiliations
Hiroki Kishikawa, Yoshihiro Makimoto, Kensuke Inoshita, Sanae Igarashi, Nobuo Goto, Shin-ichiro Yanagiya

Tokushima University, Faculty of Engineering, Department of Optical Science and Technology, 2-1 Minamijosanjima-cho, Tokushima, 770-8506, Japan

Opt. Eng. 55(5), 057104 (May 31, 2016). doi:10.1117/1.OE.55.5.057104
History: Received March 11, 2016; Accepted May 3, 2016
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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.

© 2016 Society of Photo-Optical Instrumentation Engineers

Citation

Hiroki Kishikawa ; Yoshihiro Makimoto ; Kensuke Inoshita ; Sanae Igarashi ; Nobuo Goto, et al.
"Improvement of contrast ratio in quadriphase-shift-keying optical label recognition with passive optical waveguide circuit", Opt. Eng. 55(5), 057104 (May 31, 2016). ; http://dx.doi.org/10.1117/1.OE.55.5.057104


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