A Phase Modulation Based and Frequency Stabilized Optoelectronic Oscillator Using a Self-Phase Locking Loop

A phase modulation based and frequency stabilized optoelectronic oscillator (OEO) by use of a self-phase locking loop (SPLL) is demonstrated. This SPLL is utilized to control the shifted phase of a tunable phase shifter in the oscillating loop. In this way, the frequency stability of this OEO can be improved without the need of an external RF source. The experimental results for a 10-GHz OEO show that the frequency fluctuations are decreased to less than 7 kHz within an hour, and the Allan deviation is reduced by 2 orders of magnitude.