Generating a hexagonal lattice wave field with a gradient basis structure.

We present a new, single-step approach for generating a hexagonal lattice wave field with a gradient local basis structure. We incorporate this by coherently superposing two (or more) hexagonal lattice wave fields, which differ in their basis structures. The basis of the resultant lattice wave field is highly dependent on the relative strengths of constituent wave fields, and a desired spatial modulation of basis structure is thus obtained by controlling the spatial modulation of relative strengths of constituent wave fields. The experimental realization of gradient lattice is achieved by using a phase-only spatial light modulator (SLM) in an optical 4f Fourier filter setup where the SLM is displayed with a numerically calculated gradient phase mask. The presented method is wavelength independent and is completely scalable, making it promising for microfabrication of corresponding structures.