Quadrature Squeezing and IQ De-Multiplexing of QPSK Signals by Sideband-Assisted Dual-Pump Phase Sensitive Amplifiers

Mingyi GAO  Takayuki KUROSU  Karen SOLIS-TRAPALA  Takashi INOUE  Shu NAMIKI  

Publication
IEICE TRANSACTIONS on Communications   Vol.E98-B   No.11   pp.2227-2237
Publication Date: 2015/11/01
Online ISSN: 1745-1345
Type of Manuscript: PAPER
Category: Fiber-Optic Transmission for Communications
Keyword: 
optical fiber communication,  optical signal processing,  optical phase sensitive amplifier,  optical phase locked loop,  

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Summary: 
High gain extinction ratio and stable control of the phase in phase sensitive amplification are fundamental to realize either phase regeneration or quadrature squeezing of phase modulated signals in an efficient and robust manner. In this paper, we show that a combination of our previously demonstrated “sideband-assisted” dual-pump phase sensitive amplifier with a gain extinction ratio of more than 25dB, and a phase-locked loop based stabilization technique, enable efficient QPSK quadrature squeezing. Its stable operation is exploited to realize phase de-multiplexing of QPSK signals into BPSK tributaries. The phase de-multiplexed signals are evaluated through measurement of constellation diagrams, eye diagrams and more importantly, BER curves. The de-multiplexed BPSK signals exhibited an OSNR penalty of less than 1dB compared to the back-to-back BPSK signals.