Arbitrary-frequency optical millimeter-wave generation for radio over fiber systems

The arbitrary-frequency optical microwave or millimeter (mm)-wave signals, ranging from 25 to 325 -GHz with 25-GHz spacing, can be simultaneously generated based on the generation technology of multi-wavelength laser source followed by a wavelength selected switch (WSS). These multi-wavelength signals are realized by cascading a phase modulator (PM) and a Mach-Zehnder intensity modulator. This technology is capable of generating 11 multi-wavelengths from single CW lightwave with less than 2-dB maximum power difference. One reconfigurable WSS with one input and four output ports is employed to select multiple optical mm-wave signals with a minimal frequency spacing of 25 GHz.