Optimum bias point in broadband subcarrier multiplexing with optical IQ modulators


This paper develops a theoretical analysis of the tradeoff between carrier suppression and nonlinearities induced by optical IQ modulators in direct-detection subcarrier multiplexing systems. The tradeoff is obtained by examining the influence of the bias conditions of the modulator on the transmitted single side band signal. The frequency components in the electric field and the associated photocurrent at the output of the IQ modulator are derived mathematically. For any frequency plan, the optimum bias point can be identified by calculating the sensitivity gain for every subchannel. A setup composed of subcarriers located at multiples of the data rate ensures that the effects of intermodulation distortion are studied in the most suitable conditions. Experimental tests with up to five QPSK electrical subchannels are performed to verify the mathematical model and validate the predicted gains in sensitivity.

Publication DOI: https://doi.org/10.1109/JLT.2014.2384838
Divisions: College of Engineering & Physical Sciences > Aston Institute of Photonics Technology (AIPT)
Additional Information: © 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Funding: EI CFTD (Grant CF/2011/1627), SFI Grants 09/IN.1/12653 and 10/CE/I1853 and EPSRC (Grant EP/L000091/1).
Uncontrolled Keywords: carrier to signal power ratio (CSPR),nonlinear distortion (NLD),optical IQ modulator,subcarrier multiplexing (SCM),Atomic and Molecular Physics, and Optics
Publication ISSN: 0733-8724
Last Modified: 21 May 2024 07:09
Date Deposited: 16 Mar 2015 14:05
Full Text Link: http://ieeexplo ... rnumber=6994254
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2015-01-01
Published Online Date: 2014-12-19
Authors: Gutiérrez, Fernando A.
Perry, Philip
Smyth, Frank
Ellis, Andrew D. (ORCID Profile 0000-0002-0417-0547)
Barry, Liam P.



Version: Accepted Version

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