Bicontinuity analysis of multibeam interference three-dimensional periodic structures: volume fractions and interface areas.

Bicontinuous structures are an important subset of three-dimensional periodic structures. In multibeam interference structures, the conditions for bicontinuity depend on the beam parameters and the exposure dose. As described in the present work, these conditions can be applied to establish the range of bicontinuity for any multibeam-interference-produced structure. In addition to the bicontinuity range, the analysis yields the volume fraction of the constituent materials and the normalized interface areas. This analysis has been performed for rhombohedral and woodpile lattices as well as their cubic structure limiting cases. A sphere-at-each-lattice-site model for each of the cubic cases has also been developed for comparison. The multibeam interference structures were investigated for representative media and for various incident polarizations.