Frequency Stabilization of an Optoelectronic Oscillator Based on Phase-Locked-Loop

Abstract

In this paper, frequency stabilization of an X-band optoelectronic oscillator (OEO) is obtained by phase locking to an oven-controlled crystal oscillator (OCXO) through a fractional phase-locked loop (PLL). The relationship between the loop transfer characteristic of PLL and the phase noise of the oscillation is analyzed. The overall phase noise performance of the OEO is improved with the self-injection-locking (SIL) approach, where the phase noise of the OEO is suppressed for over 20 dB within frequency offsets from 10 Hz to 10 kHz. The phase noise of the PLL-locked SIL OEO is −55 dBc/Hz at 10 Hz offset and −124 dBc/Hz at 10 kHz offset and the frequency overlapping Allan deviation (ADEV) reaches 1.14 × 10−11 at average time of 100 s, proves the high frequency stability of the obtained output.