Inverse relationship between the OEO Q-factor and vibration sensitivity

Abstract

External vibrations induce phase noise in low noise oscillators such as the OEO (opto-electronic oscillator). The g-sensitivity quantifies the efficiency of this process. In fiber-based OEOs, vibrations of the fiber spool dominate the generation of phase noise. In this case, we observe decreasing g-sensitivity with increasing Q-factor (i.e., fiber length). This result indicates the interplay of two effects. First, only a portion of the optical fiber is affected by vibrations of the spool, even though the entire spool is subjected to vibrations. For the spools that we studied, the effective length is less than 500 m. Second, as the Q-factor increases, an OEO “filtering” effect reduces the phase noise that is induced by a constant magnitude perturbation. These results can be used to optimize the g-sensitivity of fiber-based OEOs by either reducing it for low phase noise RF generation or increasing it for sensing applications.