Resonant Widely Tunable Opto-Electronic Oscillator

We experimentally demonstrate a widely tunable opto-electronic oscillator (TOEO) based on a tunable optical resonant filter and a wideband phase modulator. The oscillator can be tuned in the range of 2-15 GHz, limited by the bandwidth of the RF components utilized in the loop, with a tuning speed greater than 1 GHz/μs. The TOEO, with 220 m fiber link used as the high Q element, is characterized with phase noise less than -100 dBc measured at 10 kHz frequency offset. The agile tunable optical filter in the TOEO is a whispering gallery mode resonator made of lithium tantalate crystal. We develop a theoretical model for the TOEO and find a good agreement between the measurement results and the theoretical predictions.