High-performance microwave-photonic links

Microwave links have become key components in many communications, defense, and scientific optical system applications. Therefore work continues to devise new link technologies and system concepts that maximize link performance. In this paper we review recent progress towards high spur-free dynamic range links, comparing the most attractive new approaches, those using optical phase modulation (PM), with the well-established reference standard - the Mach-Zehnder-modulator based link. It becomes evident that links using differential PM offer some practical advantages, but with only modest performance improvements. In contrast, PM using coherent detection can offer very high performance, but large technical barriers remain.