Ultrahigh-factor frequency multiplication based on optical sideband injection locking for broadband linear frequency modulated microwave generation

In this paper, we propose and demonstrate a novel photonics-enabled frequency multiplication system with an ultrahigh multiplication factor (MF) for broadband linear frequency modulated (LFM) microwave generation. A pair of distributed feedback (DFB) lasers are injection-locked to two optical sidebands with different orders, which are excited by a narrow-band LFM waveform with a frequency range of 2∼3 GHz. Frequency-multiplied LFM waveforms are generated by beating the two DFB outputs. Thanks to the injection locking, the frequency-multiplied signals have excellent spurious suppression and linearity. The measured spurious suppression ratio exceeds 21.4 dB and the linearity is better than 1 × 10−5. The MF reconfigurability and the central frequency tunability are also demonstrated. A series of 20-fold frequency-multiplied LFM waveforms with different central frequencies and a 30-fold frequency-multiplied signal with a frequency range from 16 GHz to 46 GHz are generated. Moreover, a feedback setup is employed to stabilize the waveform phase against environmental interferences. The measured standard deviation of the remaining phase jitter is around 5.5 ∘ .