Characterization of ultra-violet-induced changes in planar waveguides

Engineering UV-photosensitivity in planar lightwave circuits by plasma enhanced chemical vapour deposition

“…Two silica/silicon bi-material systems were prepared with high ion bombardment (sample A-by powering substrate electrode) and low ion bombardment (sample B-by grounding substrate electrode) conditions, during PECVD deposition. Process parameters and other details for the silica deposition can be found in [10]. The as-deposited samples were irradiated with an ArF excimer laser at 193 nm with cumulative fluences (F = 0.5, 1, 1.5, 2.5, 3.5, 5, 6.5 and 8 kJ cm −2 ) at a repetition rate of 20 Hz and pulse energy of 11-32 mJ.…”

“…The shift in fringe pattern (arising from the Farby-Perot cavity formed by the air/SiO 2 and SiO 2 /Si interfaces) detected in the VUV spectra were used to determine the UV induced changes in the index of refraction ( n ∼ 630 nm). Details of the method can be found in [10]. Data for sample B, shown in figure 1, were taken from the same reference.…”

“…This offers new possibilities for monolithic integration with temperature sensitive active components. It was also shown that the low temperature PECVD technology is capable of producing UV-photosensitive materials that are of importance for the realization of compact and low-cost optical add-drop multi-demultiplexer [2].…”