Fabrication of polymer photonic crystal superprism structures using polydimethylsiloxane soft molds

We presented a soft lithography technique of fabricating polymer photonic crystal superprism structures using elastomeric polydimethylsiloxane templates. Dense two-dimensional photonic crystal superprism structures with feature sizes of 150 - 500 nm and aspect ratios of up to 1.25 were replicated. Large field size and easy fabrication are two major advantages when compared with other imprint technology. Atomic force microscopy images showed that the molded structures had high fidelity to the masters. Less than 3% reduction of the depth in the molded structures was achieved with respect to the master. The increase of the surface roughness from the master to the molded structures is minimal. The issue of pattern collapse during pattern transfer of submicron structures was analyzed against the pattern dimensions and aspect ratios; and the experimental results were found in agreement with a prior theory. We also experimentally demonstrated the superprism effect in two-dimensional photonic crystal structure at near-infrared wavelength. The propagation beam changed 39° in the photonic crystal with respect to the input wavelength varying from 1546 to 1572 nm . Such an effective, low cost, and high throughput soft lithography technique could find wide use in making photonic crystal based nanostructures.