Coherent-detection of narrow-linewidth millimeter-wave and microwave subcarrier signals for future mobile/personal communications

Optical wireless offers broadband telecommunication services in confined and densely populated environments. It also avoids the utilisation of the scarce and already-congested radio spectrum. However, the optical transmission power in optical wireless systems is restricted to a level that may severely degrade the system performance because of human-safety reasons. A coherent-detection technique for very narrow linewidth millimeter-wave and microwave subcarrier signals is investigated and demonstrated. This technique is particularly suitable for power-limited optical wireless systems. In addition, wide channel-tunability and improved receiver-sensitivity are supported even with cheap, wide-linewidth semiconductor lasers, without using expensive optical amplifiers