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Four wave mixing in silicon hybrid and silicon heterogeneous micro photonic structures

Electronic nonlinearities can lead to ultra-fast refractive index switching. This dynamic refractive index change can be used to shift wavelengths as well as to mix pulses of different center wavelengths. Due to its high refractive index silicon is suitable for tightly focusing light and generating high intensities required for such nonlinear effects, however high nonlinear losses in silicon (two photon absorption and absorption by free carriers generated via two photon absorption) limit transmission of high power pulses in silicon. Polymers and chalcogenide glasses have an improved nonlinear figure of merit (ration of nonlinear effect to nonlinear losses) and also don't show free carrier absorption. Due to acceptable levels of losses from generated free carriers, silicon organic hybrid or silicon glass heterogeneous structures offer to achieve high conversion efficiencies and large net gain in micro photonic devices, which can be used for wavelength conversion, parametric amplification and parametric oscillators, or for the generation of entangled photon pairs. We show both theoretical estimates and experimental results for four wave mixing conversion efficiencies in silicon hybrid and silicon heterogeneous structures.