Widely tunable RF photonic filter using WDM and a multichannel chirped fiber grating

A widely tunable RF photonic filter based on a multichannel chirped fiber Bragg grating (MCFG) is demonstrated. This topology is capable of producing continuously tunable high-frequency responses using narrow-band tunable laser sources without introducing spurious signals within the designed passband. Similar filters utilizing single-channel dispersion may exhibit degraded performance due to the mixing of the optical carriers whose beat frequencies fall within the bandwidth of the photodetector. The MCFG-based technique maintains low insertion loss through the use of wavelength division multiplexing of the optical sources, while being readily extendable to allow for greater tuning ranges, higher resolutions, and fast filter tuning and reconfiguration speeds.