Coherent Difference Frequency Generation in Nonlinear Photonic Crystals

Two-dimensional lattices of the optical nonlinearity implemented by periodic poling in
$\chi^{(2)}$
materials afford additional degrees of freedom for enhanced gains in optical parametric generation [1–2] and the generation of multipartite photon entanglement in compact device formats [3]. So far all investigations have considered single-frequency excitation of the crystals in classical or quantum parametric downconversion regimes. However, the effects underpinned by the coherent coupling of multiple nonlinear resonances unique to 2D lattices, may be expected to further enlarge the spectrum of possibilities also in suitably seeded coherent parametric amplification and difference frequency generation (DFG) processes.