A tunable electro-optic modulation (EOM) comb generator includes a frequency locking optoelectronic oscillator (OEO) loop including RF electrical components including a phase shifter (PS1), a splitter, and optical components including an intensity modulator (IM) coupled to receive light from a light source and to couple modulated light generated to a frequency locking loop including a frequency shifter, a first phase modulator (PM1), and a periodic optical filter (POF), such as an etalon or resonator. The POF is for optically filtering the OEO loop to generate an optical output and the splitter is for generating RF electrical outputs including at least one RF output coupled to an input of the IM and another RF output coupled to an EO comb including at least a phase modulator. The EO comb combines the optical output and the another RF output to generate a broadband optical frequency comb output.