Performance Analysis of All-Optical Wavelength-Shift-Free Format Conversion from QPSK to Two BPSK Tributaries Using FWM and Interference

Rina ANDO  Hiroki KISHIKAWA  Nobuo GOTO  Shin-ichiro YANAGIYA  Lawrence R. CHEN  

IEICE TRANSACTIONS on Electronics   Vol.E99-C   No.2   pp.219-226
Publication Date: 2016/02/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.219
Type of Manuscript: Special Section PAPER (Special Section on Recent Advances in Photonics Technologies and Their Applications)
optical processing,  modulation format,  four-wave mixing,  QPSK,  BPSK,  

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Conversion between multi-level modulation formats is one of key processing functions for flexible networking aimed at high spectral efficiency (SE) in optical fiber transmission. The authors previously proposed an all-optical format conversion system from binary phase-shift keying (BPSK) to quadrature PSK (QPSK) and reported an experimental demonstration. In this paper, we consider its reversed conversion, that is, from QPSK to BPSK. The proposed system consists of a highly nonlinear fiber used to generate complex conjugate signal, and a 3-dB directional coupler used to produce converted signals by interfering the incident signal with the complex conjugate signal. The incident QPSK stream is converted into two BPSK tributaries without any loss of transmitting data. We show the system performances such as bit-error-rate and optical signal-to-noise ratio penalty evaluated by numerical simulation.