Tunable Optoelectronic Oscillator Incorporating a Single Passband Microwave Photonic Filter

A wideband and continuously tunable optoelectronic oscillator (OEO) incorporating a single passband microwave photonic filter (MPF) is proposed and experimentally demonstrated. The single passband MPF is implemented using a broadband light source, a Mach-Zehnder interferometer (MZI) in which a phase modulator is incorporated in one arm, a dispersion compensating fiber (DCF), and a photodetector (PD). The light wave from the broadband light source is sent to the MZI, and the output signal from the MZI is sent to the DCF and then detected at the PD. The overall operation is equivalent to a single passband MPF with the central frequency of the passband tunable by tuning the length difference between the two arms of the MZI. By incorporating the MPF into an OEO, a microwave signal with a tunable frequency is generated. The proposed OEO is experimentally evaluated. A microwave signal with a tunable frequency from 1 to 12 GHz and a tuning step of 0.5 GHz is generated. The phase noise performance of the generated microwave signal is evaluated. At 6.02 GHz, the phase noise is measured to be -107 dBc/Hz at an offset of 10 kHz.