Proximity field nanopatterning of azopolymer thin films.

A method for inscribing surface relief gratings in azopolymer thin films via proximity field nanopatterning is reported. Azopolymers prepared by ring opening metathesis polymerization were cast as thin films and brought into conformal contact with transparent polydimethylsiloxane phase masks. Irradiation of the film surface through the phase masks induces mass transport of azopolymer that generates surface relief structures on the basis of the intensity modulation of the light by structures on the phase mask. The experimental images obtained matched well with those produced by optical simulation. A wide variety of structures could be inscribed in the film surface which depended on the molecular weight of the azopolymer and irradiation time. Control experiments conducted suggest that the process is entirely photonic and that the presence of the phase mask on the film surface did not affect the inscription process.

Three-dimensional nanofabrication with elastomeric phase masks.

This Feature Article reviews recent work on an optical technique for fabricating, in a single exposure step, three-dimensional (3D) nanostructures with diverse structural layouts. The approach, which we refer to as proximity field nanopatterning, uses conformable, elastomeric phase masks to pattern thick layers of transparent, photosensitive materials in a conformal contact mode geometry. Aspects of the optics, the materials, and the physical chemistry associated with this method are outlined. A range of 3D structures illustrate its capabilities, and several application examples demonstrate possible areas of use in technologies ranging from microfluidics to photonic materials to density gradient structures for chemical release and high-energy density science.

Molded transparent photopolymers and phase shift optics for fabricating three dimensional nanostructures.

This paper introduces approaches that combine micro/nanomolding, or nanoimprinting, techniques with proximity optical phase mask lithographic methods to form three dimensional (3D) nanostructures in thick, transparent layers of photopolymers. The results demonstrate three strategies of this type, where molded relief structures in these photopolymers represent (i) fine (<1 microm) features that serve as the phase masks for their own exposure, (ii) coarse features (>1 microm) that are used with phase masks to provide access to large structure dimensions, and (iii) fine structures that are used together phase masks to achieve large, multilevel phase modulations. Several examples are provided, together with optical modeling of the fabrication process and the transmission properties of certain of the fabricated structures. These approaches provide capabilities in 3D fabrication that complement those of other techniques, with potential applications in photonics, microfluidics, drug delivery and other areas.