Generation of permanent optically induced second-order nonlinearities in optical fibers by poling

Abstract

It is shown that large permanent enhancements in second-order optical nonlinearity can be induced in germanosilicate fibers (both pure and codoped with phosphorus) by application of a transverse dc electric poling field in the presence of high-intensity light. The macroscopic inversion symmetry of the core material is broken by the excitation and alignment of defect centers. Significant frequency doubling results despite the absence of phase matching. The saturation (with both increasing dc field and increasing intensity) of this effect is investigated.