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Three-dimensional metallodielectric photonic crystals were created by fabricating a micron-scale polymeric template using multiphoton direct laser writing (DLW) in SU-8 and conformally and selectively coating the template with copper (Cu) via nanoparticle-nucleated electroless metallization. This process deposits a uniform metal coating, even deep within a lattice, because it is not directional like sputter-coating or evaporative deposition. Infrared reflectance spectra show that upon metallization the optical behavior transitions fully from a dielectric photonic crystal to that of a metal photonic crystal (MPC). After depositing 50 nm of Cu, the MPCs exhibit a strong plasmonic stop band having reflectance greater than 80% across the measured part of the band and reaching as high as 95% at some wavelengths. Numerical simulations match remarkably well with the experimental data and predict all dominant features observed in the reflectance measurements, showing that the MPCs are structurally well formed. These data show that the Cu-based process can be used to create high performance MPCs and devices that are difficult or impossible to fabricate by other means.

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There is tremendous demand for numerical methods to perform rigorous analysis of devices that are both large scale and complex throughout their volume. This can arise when devices must be considered with realistic geometry or when they contain artificial materials such as photonic crystals, left-handed materials, nanoparticles, or other metamaterials. The slice absorption method (SAM) was developed to address this need. The method is fully numerical and able to break large problems down into small pieces, or slices, using matrix division or Gaussian elimination instead of eigensystem computations and scattering matrix manipulations. In these regards, the SAM is an attractive alternative to popular techniques like the finite-difference time domain method, rigorous coupled-wave analysis, and the transfer matrix method. To demonstrate the utility of the SAM and benchmark its accuracy, reflection was simulated for a photonic crystal fabricated in SU-8 by multiphoton direct laser writing. Realistic geometry was incorporated into the model by simulating the microfabrication process, which yielded simulation results that matched experimental measurements remarkably well.

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