Optical waveguides in LiNbO3 formed by ion implantation |
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Authors: | G L Destefanis J P Gailliard P D Townsend |
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Institution: | 1. Commissariat à l'Energie Atomique-Leti NCE-85 X , 38041, Grenoble, France;2. Commissariat à l'Energie Atomique-Leti NCE-85 X , 38041, Grenoble, France;3. M.A.P.S. University of Sussex , Falmer, Brighton, BN1-9QH, G.B. |
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Abstract: | Abstract Ion implantation in LiNbO3 can be used to modify the refractive index. The change in indices, n 0 n e results from the damage formed by energy deposited by the (dE/dx)nuclear collisions between the ions and the lattice and is independent of the ion species. A saturation change in index of some ?7% occurs after a deposition of 1023 keV cm?3 at 300K, greater changes of ?9 % occur with implants at 77K. Annealing studies indicate the optical absorption formed during irradiation is removed below 200°C whereas the index changes exist up to 400°C. For optical waveguide production a negative change in the index is not ideal as the damaged layer cannot directly act as the region of optical confinement. However the (dE/dx)electronic term is unimportant and so we have been able to form optical waveguides by ion implantation with light energetic ions (e.g. MeV He+ ions) because the damaged layer is then formed beneath an unchanged high index surface layer. This retains the desirable electrooptic properties of the single crystal LiNbO3. The experimentally observed waveguide modes are in accord with our theoretical predictions of the refractive index profiles. |
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Keywords: | scattering charge exchange neutrals directional dependence valence electrons |
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