Fiber Optic Subcarrier Transmission Systems Using Coherence Multiplexing Techniques for Broad-Band Distribution Networks

Hideyuki UEHARA  Iwao SASASE  Mitsuo YOKOYAMA  

IEICE TRANSACTIONS on Communications   Vol.E80-B       pp.1027-1034
Publication Date: 1997/07/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Category: Optical Communication
SCM,  coherence multiplexing,  IMD,  FM demodulation,  broad-band distribution network,  

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Fiber optic subcarrier transmission system using coherence multiplexing techniques for broad-band distribution networks is proposed. This system makes it possible to improve the laser linewidth requirement and also to eliminate the effect of intermodulation distortion (IMD) which is serious problem in subcarrier multiplexed (SCM) system. In the proposed system, the frequency difference, fo, between the reference light and the signal light makes it possible to generate the broadand FM signal after photodetecting. Thus, an increase in the modulation index provides a corresponding increase in receiver sensitivity. We analyze the fundamental performance of the proposed system and derive the signal-to-noise ratio (SNR) at the output of FM demodulator by taking the threshold effect and spike noise into account. The proposed system can achieve the total capacity in excess of 10 GHz, and thus it is attractive for multichannel broad-band distribution networks.