The opto-electronic oscillator (OEO): Review and recent progress

This paper reviews developments over the past two decades related to the Opto-Electronic Oscillator (OEO). Various approaches for realization of the OEO architecture are discussed. Recent advances related to generation of spectrally pure signals with a compact configuration of OEO, based on optical whispering gallery mode (WGM) resonators are discussed. Finally, based on the current development, future versions of the OEO, which combine the optoelectronic feedback loop with a Kerr comb frequency generator made with a crystalline WGM resonator, are mentioned.