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Abstract

We experimentally demonstrate how sum frequency generation (SFG) and difference frequency generation (DFG) of 150 fs pulses can be enhanced and serve as diagnostics for leaky eigenmodes in a two-dimensional GaAs photonic crystal waveguide. SFG at 795 nm is obtained in reflection from s-polarized 1900 nm and p-polarized 1360 nm pulses, with both input beams coupled to leaky eigenmodes; the SFG is enhanced by > 350x compared to that from an untextured GaAs surface. We are able to detect Drude induced subnanometer blueshifts of the SFG, corresponding to refractive index changes of <= 10(-3). DFG of 1360 nm light obtained in reflection from s-polarized 1900 nm and p-polarized 793 nm pulses displays an enhancement of > 500x via three different leaky eigenmodes. As the 793 nm beam polarization is varied from p polarized to right and left circularly polarized, the DFG remains essentially linearly polarized but with a reduced, albeit different, intensity for right and left circularly polarized 795 nm pulses. Futhermore, the plane of polarization also rotates by different amounts for the left and right circularly polarized light, demonstrating interference of the components generated by s- and p-polarized 793 nm pulses. Overall, our results demonstrate how enhanced DFG and SFG from leaky eigenmodes can be used to characterize their properties more precisely than linear optical techniques. (c) 2006 American Institute of Physics.