| Title |
Transmission Grating Formation in High Refractive-index Amorphous Thin Films Using Focused-Ion-Beam Lithography |
| Authors |
신경(Shin, Kyung) ; 김진우(Kim, Jin-Woo) ; 박정일(Park, Jeong-Il) ; 이현용(Lee, Hyun-Yong) ; 이영종(Lee, Young-Jong) ; 정홍배(Chung, Hong-Bay) |
| Keywords |
Focused Ion Beam(FIB) milling, polarization effect, birefringence effect, maximum diffraction efficiency |
| Abstract |
In this study, we investigated the optical properties of sub-wavelength a-Si thin film transmission gratings, especially the polarization effect, the phase difference and the birefringence by using linearly polarized He-Ne laser beam (632.8nm). The a-Si transmission grating of the thickness of < 0.1 μm with four-type period(Λ = 0.4 μm and 0.6 μm for sub-wavelength and Λ = 1.0 μm and 1.4 μm for above-wavelength) on quartz substrates have been fabricated using 50 KeV Ga+ Focused-Ion-Beam(FIB) Milling and CF_4Reactive-Ion-Etching(RIE) method. Finally, we obtained the trating array of a-Si thin film with a period 0.4 μm, 0.6 μm, 1.0 μm, 1.4 μm which have nearly equal finger spacing and width, sucessfully. Especially, for gratings with Λ = 0.6 μm(linewidth=0.25 μm, linespace=0.35μm), the ηmax at θ_в=17.0° is estimated to be 96%. As the results, we believe that the sub-wavelength grating arrayed a-Si thin film has the applicability as the optical device and components. |