Coupling length phase matching scenarios in dual-core silica fibers

We analyze optical dual core silica fiber configurations that can be achieved to obtain phase matched third-order nonlinear optical frequency conversion to obtain farther infrared laser sources from near-infrared lasers. The phase matching principle is based on the coupling length phase matching (CLPM) principle, which allows to tune the phase matching condition by tuning the distance between the two cores in the fiber. We describe the corresponding phase matching tuning curves for different choices of pump lasers and discuss the advantages and limitations of the technique.