Super-homogeneous microwave-photonic gain and its impact on optoelectronic oscillators

We develop the theory of microwave-photonic (MWP) gain saturation when two tones (one large and one small) are transmitted over an intensity-modulated direct-detection photonic link. We show that MWP gain is “super-homogeneous” with the larger signal saturating the gain of the smaller signal faster than the saturation of its own gain. This model is applied to the steady-state simulation of an optoelectronic oscillator (OEO) incorporating slab-coupled optical waveguide (SCOW) based laser and photodiode components. Our simulations and experimental measurements indicate that large sidemode suppression can be achieved even when multiple modes are supported within the cavity.