Multiband microwave waveforms transmitting system using dual fiber combs

Abstract

In this work, a multiband microwave waveforms transmitting system was demonstrated based on all-optical dual fiber combs. Two optical fiber frequency combs via cascaded four waves mixing process ensure the coherence of the system by sharing the pump light. The high-speed frequency tuning of the pump laser will be transferred to each newly generated comb line through the nonlinear effect in the fiber. The comb pairs of the same order obtained through filtering transform the frequency chirp in the optical domain to the frequency chirp in the electrical domain after being beat on the PD. By changing the parameters of the control signal, the center frequency, bandwidth, PRF and envelope of the multi band microwave signal can be flexibly reconfigurable. Thanks to the coherence of dual optical frequency combs, microwave signals all show excellent line-type, high signal to noise ratio and no burrs. As a result, the chirped microwave signals of triangle wave, sine wave and sawtooth wave types are obtained at the repetition rate of 500 Hz. Overall, multi-band chirped microwave generation system based on all-optical system provides a practical device for transmitting and receiving multi band radar.