Microwave photonics has attracted much research attention during the last two decades, due to its
combining the advantages of both wireless communications and photonics, such as the mobility of
wireless communications, large bandwidth, low loss, lightweight, and immunity to electromagnetic
interference. Recently, microwave photonics has been explored more intensively at the subsystem
and application levels. Many microwave photonic filter architectures [1]–[3] have been developed
for particular applications, e.g., a tunable microwave photonic filter for noise and interference suppression
in Universal Mobile Telecommunications System base stations has been reported [4].
In radio-over-fiber (RoF) systems, subcarrier multiplexing technology can further enhance the
system transmission capacity. In the central station (CS), subcarriers with different frequencies are
modulated by different kinds of data streams, and then, these subcarriers are transmitted through
one fiber link to the remote antenna units (RAUs) [5]. In each RAU, a demultiplexing module
should be available to pick up its own data stream, and one microwave filter can be employed as
the demultiplexer. However, when the subcarrier frequency increases, e.g., in microwave/
millimeter-wave (mmW)-over-fiber systems, the frequency could be up to 60 GHz, the traditional
electrical microwave filter is hard to implement, or is very expensive. As the key advantage of the