Phase noise mitigation of QPSK signal utilizing phase-locked multiplexing of signal harmonics and amplitude saturation

Authors

Amirhossein Mohajerin-Ariaei, Morteza Ziyadi, Mohammad Reza Chitgarha, Ahmed Almaiman, Yinwen Cao, Bishara Shamee, Jeng-Yuan Yang, Youichi Akasaka, Motoyoshi Sekiya, Shigehiro Takasaka, Ryuichi Sugizaki, Joseph D. Touch, Moshe Tur, Carsten Langrock, Martin M. Fejer, and Alan E. Willner

Abstract

We demonstrate an all-optical phase noise mitigation scheme based on the generation, delay, and coherent summation of higher order signal harmonics. The signal, its third-order harmonic, and their corresponding delayed variant conjugates create a staircase phase-transfer function that quantizes the phase of quadrature-phase-shift-keying (QPSK) signal to mitigate phase noise. The signal and the harmonics are automatically phase-locked multiplexed, avoiding the need for phase-based feedback loop and injection locking to maintain coherency. The residual phase noise converts to amplitude noise in the quantizer stage, which is suppressed by parametric amplification in the saturation regime. Phase noise reduction of ∼40% and OSNR-gain of ∼3  dB at BER 10−3 are experimentally demonstrated for 20- and 30-Gbaud QPSK input signals.

Journal

Optics Letters

Volume

40

Number

14

Date

07/2015
AttachmentSize
Mohajerin OL20152.55 MB