Ultrahigh-factor frequency multiplication based on optical sideband injection locking for broadband linear frequency modulated microwave generation
Jiading Li, Xiaoxiao Xue, Jichen Zhang, Zhujun Xue, Bofan Yang, Shangyuan Li, Xiaoping Zheng
Abstract
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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msup> <mml:mi/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>∘</mml:mo> </mml:mrow> </mml:msup> </mml:math> .