An All-Optical Base Station for MMW Micro-Cell Radio Using Microwave-Optical Mixing in LiNbO3 Modulators

Howard J. THOMAS  Nobuaki IMAI  Eiichi OGAWA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E80-C   No.1   pp.74-80
Publication Date: 1997/01/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Devices, Packaging Technology, and Subsystems for the Optical Access Network)
Category: 
Keyword: 
millimeter wave,  microwave-optical mixing,  Mach-Zehnder external optical modulator,  mobile communications,  

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Summary: 
This paper proposes a new approach for distributing millimeter wave signals from a central location to micro-base-stations using optical fiber links. The links utilize two Mach-Zehnder external optical modulators (EOMs) to perform all optical down-conversion, eliminating the need for a local oscillator or laser diode in the micro-base-station. A simple model of the EOMs is developed to illustrate the principle of dual-EOM mixing. The characteristics of conversion loss and intermodulation are examined for two cases: where the EOMs are operated in the linear mode and where the local oscillator's EOM is biased as a frequency doubling modulator. Additionally, we examined the use of an optical amplifier to reduce conversion loss for these two cases. The measured conversion loss of the link was 82 dB, and we estimated this could be reduced to about 48 dB by employing an optical amplifier and a more efficient EOM for RF reception.