Several high-intensity resonances were observed There are experimental difficulties in comparing the FDTD-derived optical properties of the monolithic structure to experimental materials. As shown in Figure , the PS nanosphere template is crystalline on short length scales (roughly 10 µm) but defective on larger ones. This makes it difficult to measure the transmission and reflection spectra of these layers in a UV-vis spectrometer, where the probe size is much larger (> 1 mm x 1 mm). This suggests that the high absorption enhancements observed in the FDTD simulations may not be accessible to large-area applications such as photovoltaics.