A Feasibility Study of DSP-Enabled Cancellation of Random Phase Noise Caused by Optical Coherent Transceivers in Next-Generation Optical Access Systems

Sang-Yuep KIM
Jun-ichi KANI
Hideaki KIMURA

IEICE TRANSACTIONS on Communications   Vol.E99-B    No.12    pp.2574-2582
Publication Date: 2016/12/01
Publicized: 2016/06/28
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2016EBP3039
Type of Manuscript: PAPER
Category: Fiber-Optic Transmission for Communications
passive optical network,  optical coherent detection,  multilevel modulation,  digital signal processing,  

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This paper presents a scheme that digitally cancels the unwanted phase components generated by the transmitter's laser and the receiver's local oscillator laser; such components place a substantial limit on the performance of coherent transceivers monolithically integrated with lasers in a photonic integrated circuit (PIC). Our cancellation proposal adopts the orthogonal polarization approach to provide a reference that is uncorrelated with the data signal. We elaborate on the principle of our proposal and its digital signal processing (DSP) algorithm. Experiments on a VCSEL with a linewidth of approximately 300MHz verify that our proposal can overcome the inherent phase noise limitations indicated by simulations and experiments. Our cancellation algorithm in conjunction with CMA-based polarization control is demonstrated and evaluated to confirm the feasibility of our proposal. The achievement of greatly relaxed laser linewidth will offer a significant benefit in offsetting the technical and cost requirements of coherent transceiver PICs with lasers. Therefore, our cancellation proposal is an enabling technology for the successful deployment of future coherent-based passive optical network (PON) systems.