Nanoimprint lithography (NIL) can be used as a tool for three-dimensional nanoscale fabrication. In particular, complex metal pattern structures in polymer material are demanded as plasmonic effect devices and metamaterials. To fabricate of metallic color filter, we used silver ink and NIL techniques. Metallic color filter was composed of stacking of nanoscale silver disc patterns and polymer layers, thus, controlling of polymer layer thickness is necessary. To control of thickness of polymer layer, we used spin-coating of UV-curable polymer and NIL. As a result, ten stacking layers with 1000 nm layer thickness was obtained and red color was observed. Ultraviolet nanoimprint lithography (UV-NIL) is the most effective technique for mass fabrication of antireflection structure (ARS) films. For the use of ARS films in mobile phones and tablet PCs, which are touch-screen devices, it is important to protect the films from fingerprints and dust. In addition, as the nanoscale ARS that is touched by the hand is fragile, it is very important to obtain a high abrasion resistance. To solve these problems, a UV-curable epoxy resin has been developed that exhibits antifouling properties and high hardness. The high abrasion resistance ARS films are shown to withstand a load of 250 g/cm2 in the steel wool scratch test, and the reflectance is less than 0.4%.
Stacking technique of nanopattern array is gathering attention to fabricate next generation data storage such as plasmon
memory. This technique provides multi- overlaid nanopatterns which made by nanoimprint lithography. In the structure,
several metal nanopatterned layer and resin layer as a spacer are overlaid alternately. The horizontal position of
nanopatterns to under nanopatterns and thickness of resin layer as spacer should be controlled accurately, because these
parameters affect reading performance and capacity of plasmon memory. In this study, we developed new alignment
mark to fabricate multi- overlaid nanopatterns. The alignment accuracy with the order of 300 nm was demonstrated for
Ag nanopatterns in 2 layers. The alignment mark can measure the thickness of spacer. The relationship of spacer
thickness and position of scale bar on the alignment mark was measured. The usefulness of the alignment mark for highdensity
plasmon memory is shown.
The diffractive optical element (DOE) has the transformation function of wavefront, and its applications are forming or
homogenization of beam, and aberration correction, and so on. In this study, we evaluate possibility as storage
application of the DOE. The optical data storage using the DOE is thought of as a kind of holographic data storage
(HDS). In the HDS, digital data is recorded and read out as modulated 2-dimensional page data, instead of bit-by-bit
recording in conventional optical storages. Therefore, HDS actualize high data transfer rate. We design and optimize
phase distribution of the DOE using the iterative method with regularization. In the optimization process, we use
iterative Fourier transform algorithm (IFTA) that is known as Gerchberg–Saxton (GS) algorithm. At this time, the
regularization method is adopted to suppress minute oscillation of the diffraction pattern. Designed and optimized DOE
is fabricated by ultraviolet (UV) nanoimprinting technology. High productivity can be expected by adopting
nanoimprinting technology. DOEs are duplicated on the silicon (Si) substrate as reflection-type elements. Fabricated
DOE is evaluated in the experiment. We verify that DOE for optical data storage can be actualized through our approach.
The research and development of the holographic data storage (HDS) is advanced, as one of the high-speed, mass storage systems of the next generation. Recently, along the development of the write-once system that uses photopolymer media, large capacity ROM type HDS which can replace conventional optical discs becomes important. In this study, we develop the ROM type HDS using a diffractive optical element (DOE), and verify the effectiveness of our approach. In order to design DOE, iterative Fourier transform algorithm was adopted, and DOE is fabricated with electron beam (EB) cutting and nanoimprint lithography. We optimize the phase distribution of the hologram by iterative Fourier transform algorithm known as Gerchberg–Saxton (GS) algorithm with the angular spectrum method. In the fabrication process, the phase distribution of the hologram is implicated as the concavity and convexity structure by the EB cutting and transcribed with nanoimprint lithography. At this time, the mold is formed as multiple-stage concavity and convexity. The purpose of multiple-stage concavity and convexity is to obtain high diffraction efficiency and signal-to-noise ratio (SNR). Fabricated trial model DOE is evaluated by the experiment.