Arbitrary Microwave Waveform Generation Based on a Tunable Optoelectronic Oscillator

Photonic generation of a phase-coded or frequency-chirped microwave waveform with a tunable microwave carrier frequency using a frequency-tunable optoelectronic oscillator (OEO) is proposed and experimentally demonstrated, for the first time to the best of our knowledge. In the proposed system, the tunable OEO has functions to generate a frequency-tunable microwave signal and to output an optical sideband. The optical sideband and a portion of the light wave from the OEO laser source are sent to a polarization modulator (PolM), with their polarization directions aligned with the two principal axes of the PolM. An electrical signal is applied to the PolM, and two complementary phase-coded or frequency-chirped light waves are generated which are converted to an electrical signal by beating the light waves at a high-speed photodetector. The key significance of the technique is that a phase-coded or frequency-chirped microwave waveform with a tunable microwave carrier frequency and a re-configurable phase-coding or frequency-chirping pattern can be generated without using a separate microwave source. The technique is experimentally verified. The generation of a binary-and a polyphase-coded microwave waveform with a microwave carrier frequency at 10 and 15 GHz is demonstrated. The generation of a linearly frequency-chirped microwave waveform with a chip rate of 20.98 GHz/ns at a 10-GHz carrier frequency and 22.5 GHz/ns at a 15-GHz carrier frequency is also achieved.