Combining different photonic crystal lattices greatly enhances the performance of optical devices based on the structures, report engineers at the University of Delaware in Newark. In the Dec. 1 issue of Applied Optics, they present simulations of photonic crystal beamsplitters that employ a square lattice and of ones that incorporate both a square and a hexagonal lattice.Finite difference time-domain models of the devices revealed that replacing the square lattice with a hexagonal one in the splitter section increases the overall throughput efficiency from 50 to 90 percent. The team also investigated a four-way beamsplitter and a splitter and combiner device based on the heterostructures.