Super-homogenous saturation of microwave-photonic gain in optoeletronic oscillator systems
October 1, 2012
IEEE Photonics J., Vol. 4, No. 5, October 2012, pp. 1256-1266.
We show that the saturation characteristic of microwave-photonic gain is "superhomogeneous" such that the gain of a weaker tone saturates more rapidly than that of a stronger tone when both signals are transmitted over an intensity-modulated optical link. Using this gain model, we simulate the effect of nonlinear gain saturation on the performance of a slab-coupled optical waveguide (SCOW)-based optoelectronic oscillator (OEO). We verify our simulations with experimental measurements and show that low sidemode levels (< -110 dBc) can be achieved even when multiple modes can oscillate within the passband of the OEO loop filter.