All-optical microwave mixing and bandpass filtering in a radio-over-fiber link

An all-optical signal processor that performs both microwave mixing and bandpass filtering in a radio-over-fiber link is proposed and demonstrated. The key device in the processor is an electrooptic phase modulator which performs all-optical microwave mixing. The microwave bandpass filtering is realized by passing the mixed microwave signals through a length of single-mode fiber, acting as a dispersive device. An up- or down-converted microwave signal is obtained and other unwanted frequency components are rejected at the end of the fiber span. The use of the proposed signal processor to perform an up-conversion of a microwave signal from 3 to 11.8 GHz in a 25-km fiber link is demonstrated.