Fabrication of Tungsten-Tellurite Glass Thin Films using Radio Frequency Magnetron Sputtering Method and Optical Propert
- PDF / 273,139 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 61 Downloads / 207 Views
L6.22.1
Fabrication of Tungsten-Tellurite Glass Thin Films using Radio Frequency Magnetron Sputtering Method and Optical Property Characterization Ki-Young Yoo, Sanghoon Shin, Youngman Kim, Jong-Ha Moon, and Jin Hyeok Kim Center for Photonic Materials and Devices Department of Materials Science and Engineering, Chonnam National University 300 Yongbong-Dong, Puk-Gu, Kwangju 500-757, South Korea ABSTRACT Tungsten-tellurite glass thin films were fabricated by radio-frequency (rf) magnetron sputtering method at various processing parameters such as substrate temperatures, Ar/O2 processing gas flow ratio, processing pressure, and rf power from a 70TeO2-30WO3 target fabricated by solid–state sintering method. The effects of processing parameters on the growth rate, the surface morphologies, the crystallinity, and refractive indices of thin films were investigated using atomic force microscopy, X-ray diffractometer, scanning electron microscopy, and UV spectrometer. Amorphous glass thin films with a surface roughness of 4~6 nm were obtained only at room temperature and crystalline phase were observed in all as-deposited thin films prepared at above the room temperature. The deposition rate strongly depends on the processing parameters. It increases as the rf power increases and the processing pressure decreases. Especially, it changes remarkably as varying the Ar/O2 gas flow ratio from 40sccm/0sccm to 0sccm/40sccm. When the films were formed in pure Ar atmosphere it shows a deposition rate of ~0.2 µm /h, whereas ~1.5 µm/h when the films was formed in pure O2 atmosphere.
INTRODUCTION Erbium doped fiber amplifiers (EDFAs) have used silica or silicate glasses based fibers as host materials because the characteristics of the materials for optical fibers are similar to those of the silicate glasses. However, the full width at half maximum (FWHM) of these materials is about 45 nm with a non-flat gain profile at 1550 nm. This value of FWHM is insufficient to support the number of channels for WDM EDFA. Therefore, recently, tellurite glass has received
L6.22.2
great interest as a host material for broadband EDFAs[1-4] because it has the FWHM of about 80 nm at 1550 nm [2-5]. In addition to the large FWHM, tellurite glasses have a wide transmission region (0.35~6µm), good glass stability, the lowest vibration energy (about 780 cm-1) among glass formers, high refractive index, low processing temperature, high nonlinear refractive index, and good chemical durability [6-9]. However, tellurite glasses have two disadvantages as a host for EDFAs. First, the phonon energy of the glass is relatively low at 770 cm-1, so the 4I11/2 4 I13/2 nonradiative decay is too slow to allow pumping at 980 nm. Second, the softening point of tellurite glass is at 290 oC, which makes it exposed to thermal damage at high optical intensities [10-11]. Tungsten-tellurite glasses have been proposed to overcome these problems. Tungstentellurite glasses differ from the conventional tellurite glasses in that they contain two glassforming components, WO3 and
Data Loading...
