Amplitude and phase of shaped nonlinear excitation fields in a four-wave mixing microscope

We describe precise measurements of the amplitude and phase profiles of tightly focused nonlinear excitation fields in a four-wave mixing (FWM) microscope. By combining spatial light modulator based beam shaping with interferometric detection, we present the focal FWM excitation fields of various Hermite-Gaussian and Laguerre-Gaussian LG(01) beam modes. We observe well-defined spatial phase patterns for the focal fields associated with these beam modes. Such precise measurements of shaped nonlinear excitation fields have implications for the development of resolution enhancement schemes and tip-enhanced imaging methods in FWM microscopy. (C) 2011 American Institute of Physics. [doi:10.1063/1.3657148]