Versatile Optoelectronic Oscillator for Single-Frequency, Dual-Frequency, and Mode-Locking Oscillation

We demonstrate a versatile optoelectronic oscillator (OEO) that can seamlessly switch between single-frequency, dual-frequency, and mode-locking oscillation modes. The OEO operates by shaping the spectrum of an ASE (Amplified Spontaneous Emission) source into a cosine profile to generate multiple taps that create a microwave photonic (MWP) finite impulse response (FIR) filter through fiber dispersion. By programming the spectrum of the ASE source, we can produce multiple independent RF passbands with wide frequency tunability. Consequently, our OEO exhibits a broad frequency tuning range from 3.05 GHz to 11.12 GHz for both single-frequency and mode-locking oscillation modes. In the dual-frequency mode, the two microwave signals can be independently adjusted, covering ranges of 3.05 GHz to 3.96 GHz and 6.29 GHz to 7.41 GHz, respectively. Furthermore, our OEO shows excellent frequency stability with frequency drifts remaining below 0.2 kHz over 5 minutes in mode-locking mode without the need for any frequency stabilization. Finally, the entire structure is composed of a single cavity, making our OEO both cost-effective and compact.