Spurious-mode suppression in optoelectronic oscillators

Optoelectronic oscillators (OEOs) are promising low phase noise radio frequency sources. However, the long fiber loops required for a high Oscillator Q also lead to spurious modes (spurs) spaced too narrowly to be filtered by standard electronic devices. As a solution to this problem, the dual injection-locked OEo (DIL-OEO) has been proposed and studied. Previously, we presented experimental data demonstrating spur suppression in the DIL-OEO. We also developed theoretical models enabling us to optimize the DIL-OEO. In this work, we present data demonstrating 60 dB suppression of the nearest-neighbour spur in a high-Q OEO without increasing the phase noise within 1 kHz of the 10 GHz oscillating mode.