A method of fabricating an optical computing device using a photonic crystal-based integrated computational element is provided. The method includes selecting a photonic crystal structure with a design suite stored in a non-transitory, computer-readable medium and obtaining a transmission spectrum for the selected photonic crystal. Further, the method includes determining a predictive power of a photonic crystal-based integrated computational element for a characteristic of a sample using the transmission spectrum and a spectral database. And adjusting the transmission spectrum to improve a predictive power of the photonic crystal-based integrated computational element for measuring a characteristic of a sample being analyzed. Also, fabricating the photonic crystal structure for the photonic crystal-based integrated computational element when the predictive power surpasses a pre-selected threshold.