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A 24 GHz microwave frequency divider with variable frequency dividing ratio based on a super-harmonic injectionlocked tunable optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. Due to the nonlinearity of the dual-output Mach-Zehnder intensity modulator (DOMZM) and the photodiode (PD) used in the OEO loop, it can generate intermodulation components between the 24 GHz injection RF signal and the harmonics of the free-running OEO. If the frequency of any one of the intermodulation components locates at the locking range of the free-running OEO, the phase of the OEO will be synchronized to the 24 GHz injection RF signal. It realizes a microwave frequency divider. By tuning the oscillation frequency of the OEO to the second, third, or fourth sub-harmonic of the 24 GHz input RF signal, a microwave frequency divider with variable frequency dividing ratio of 2, 3, or 4 is realized. The achievable frequency dividing ratio is limited by the nonlinearity of the DOMZM and the injection RF power. A good phase noise performance of the OEO lead to a microwave frequency divider with low phase noise. The transient response of the RF phase of the output of the OEO during the process of super-harmonic injection locking is also measured.
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