Nonlinear time series analysis and wavelet bicoherence are used to characterize the changes to microturbulence in the radial electric field shear layer across the L to H transition in DIII-D. Time series of fluctuating floating potential and ion saturation current from the reciprocating probe array have been analysed for skewness and kurtosis as indications of intermittency in the turbulence. Provided the time series are carefully selected for stationarity, the skewness S and kurtosis K are consistent with Gaussian probability distributions in both L- and H-modes. Wavelet bicoherence analysis reveals the presence of intermittency in the coupling due to sum frequencies above 400 kHz in both the L- and H-modes. The intermittency is most pronounced in the H-mode, with the intervals of strong coupling correlated with changes in local edge plasma conditions. These results appear consistent with predictions from self-organized criticality models.