Optoelectronic oscillator using an acousto-optic delay line

We demonstrate an optoelectronic oscillator (OEO) based on an acousto-optic modulator (AOM). The free spectral range between the modes is a function of the total loop length of the OEO, which is dependent on the propagation time of the acoustic wave through the AOM. By using the huge difference in the magnitude between the speed of light and the acoustic velocity in the AOM, we can extend the effective loop length of the OEO up to 3.8 km. We have measured phase noise of the OEO. Further developments will be made by using a dual-loop configuration.