GRATING-ASSISTED PHASE-MATCHED 2ND-HARMONIC GENERATION FROM A POLYMERWAVE-GUIDE

Diffraction gratings can be used to achieve phase matching between the fundamental modes of a slab or confined waveguide. Compared with the usual techniques such as quasi-, Cerenkov, and intermodal phase matchi ng, the matching method used here involves spatial harmonies of the gu ided electromagnetic field that are generated by the corrugated gratin g. This grating acts simultaneously as a linear waveguide coupler at b oth the pump and harmonic frequencies. Using the third spatial harmoni c, we report what we believe to be the first observation of grating-as sisted phase-matched second-harmonic generation between counterpropaga ting TM(0) modes of an organic waveguide.