Photonic Generation of Linearly Chirped Microwave Waveforms With Tunable Parameters

We propose a linearly chirped microwave waveform (LCMW) generation scheme applying a stimulated Brillouin scattering (SBS)-based Fourier domain mode locked (FDML) optoelectronic oscillator (OEO). In this system, SBS-induced phase-modulation-to-intensity-modulation-conversion is adopted to build a microwave photonic filter, of which the pass-band can be rapidly tuned by adopting a high-order frequency sweeping modulation sideband as the optical carrier. Thanks to the frequency multiplication capability and the fast mode selection with a very narrow pass band, the proposed system can generate broadband LCMWs with a good frequency modulation linearity. Besides, the bandwidth, central frequency, duty cycle and repetition rate of the LCMWs can be easily adjusted to satisfy different radar applications. A proof-of-concept experiment is carried out. The results can soundly verify the feasibility as well as the flexibility of the proposed LCMW generation system.