초록 |
Fabrications of surface relief gratings (SRGs) on photosensitive organic thin films have been attracted for optoelectronic applications such as optical data storages, optical waveguides, optically controllable gratings, and liquid crystal alignment layers. Particularly, azobenzene containing organic materials which are fabricated to the stable gratings by ultraviolet or visible light below the glass transition temperature (Tg) have been reported by many researchers. The interference pattern by azo-chromorphore excitation light cause a molecular migration due to isomerization of azobenzene moieties in the azopolymer films. In this presentation, we demonstrate fabrication of SRGs with graded profile utilizing replication and deformation of poly (dimethylsiloxane) (PDMS). PDMS replica was fabricated by immersing of azopolymer SRG into the PDMS prepolymer fluids, curing in vacuum oven, and removing template. PDMS molds are able to deform because of their flexible elastomeric property. For the formation of graded profiled SRGs, PDMS replica was deformed by compression or expansion of one side of grating on PDMS surface. After the polarized Ar ion laser light penetrated into PDMS replica, this light was diffracted at the grating surface, and the interference of diffracting light caused SRGs following the profile of PDMS replica on the azopolymer thin film near PDMS grating. The surface profiles of SRGs were investigated by atomic force microscopy. |