Increase of Recognizable Label Number with Optical Passive Waveguide Circuits for Recognition of Encoded 4- and 8-Bit BPSK Labels

Hiroki KISHIKAWA  Akito IHARA  Nobuo GOTO  Shin-ichiro YANAGIYA  

IEICE TRANSACTIONS on Electronics   Vol.E100-C   No.1   pp.84-93
Publication Date: 2017/01/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E100.C.84
Type of Manuscript: PAPER
Category: Optoelectronics
code recognition,  optical waveguide circuits,  optical BPSK code,  

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Optical label processing is expected to reduce power consumption in label switching network nodes. Previously, we proposed passive waveguide circuits for the recognition of BPSK labels with a theoretically infinite contrast ratio. The recognizable label number was limited to four and eight for 4-bit and 8-bit BPSK labels, respectively. In this paper, we propose methods to increase the recognizable label number. The proposed circuits can recognize eight and sixteen labels of 4-bit BPSK codes with a contrast ratio of 4.00 and 2.78, respectively. As 8-bit BSPK codes, 64, 128, and 256 labels can be recognized with a contrast ratio of 4.00, 2.78, and 1.65, respectively. In recognition of all encoded labels, that is, 16 and 256 labels for 4-bit and 8-bit BPSK labels, a reference signal is employed to identify the sign of the optical output signals. The effect of phase deviation and loss along the optical waveguides of the devices is also discussed.