AN ALL-OPTICAL BASE STATION FOR MMW MICRO-CELL RADIO USING MICROWAVE-OPTICAL MIXING IN LINBO3 MODULATORS

This paper proposes a new approach for distributing millimeter wave si gnals from a central location to micro-base-stations using optical fib er links. The links utilize two Mach-Zehnder external optical modulato rs (EOMs) to perform all optical down-conversion, eliminating the need for a local oscillator or laser diode in the micro-base-station. A si mple model of the EOMs is developed to illustrate the principle of dua l-EOM mixing. The characteristics of conversion loss and intermodulati on are examined for two cases: where the EOMs are operated in the line ar mode and where the local oscillator's EOM is biased as a frequency doubling modulator. Additionally, we examined the use of an optical am plifier to reduce conversion loss for these two cases. The measured co nversion loss of the link was 82 dB, and we estimated this could be re duced to about 48 dB by employing an optical amplifier and a more effi cient EOM for RF reception.