Wang Xue-Lin

Effects of swift argon-ion irradiation on the proton-exchanged LiNbO3 crystal

A proton-exchanged LiNbO3 crystal was subjected to 70-MeV argon-ion irradiation. The lattice damage was investigated by the Rutherford backscattering and channeling technique. It was found that the lattice disorder induced by the proton exchange process was partially recovered and the proton-exchanged layer was broadened. It indicated that the lithium ions underneath the initial proton-exchanged layer migrated to the surface during the swift argon-ion irradiation and supplemented the lack of lithium ions in the initial proton-exchanged layer. This effect was ascribed to the great electronic energy deposition and relaxation. The swift argon-ion irradiation induced an increase in extraordinary refractive index and formed another waveguide structure beneath the proton-exchanged waveguide.

Ion-Implanted Waveguides in a Nd3+-Doped Silicate Glass

Monomode enhanced-index Nd3+-doped silicate glass waveguides fabricated by ion implantation are reported. The Nd3+-doped silicate glass was implanted by 3.0 MeV B+ ions, 3.0 MeV O+ ions and 4.5 MeV Ni2+ ions, respectively. A prism-coupling method was carried out to measure dark modes in the Nd3+-doped silicate glass using a model 2010 prism coupler. The moving fibre method was applied to measure the waveguide propagation loss. After a moderate annealing, the 3.0-MeV B+-ion implanted waveguide loss is about 3.54 dB/cm; the 3.0-MeV O+-ion implanted waveguide loss is about 5.36 dB/cm; and the 4.5-MeV the Ni2+-implanted waveguide loss is about 7.55 dB/cm. The results show that with the increasing ion mass, the loss in implanted waveguide is increased.

Analysis and Determination of Refractive Index Profiles of O2+ Ion-Implanted LiNbO3 Planar Waveguide Using Etching and Ellipsometry Techniques

The refractive index profiles of 3MeV O2+ ion-implanted planar waveguides in lithium niobate are reconstructed based on etching and ellipsometry techniques. SRIM2003 code is used to simulate the damage distribution in waveguide. It is demonstrated that the index profile of this kind of waveguide, extending to several micrometres in depth, can be determined by etching in combination with following ellipsometric measurements. A good agreement is found between the simulated damage distributions in waveguide and the index profiles based on experimental data, and the width of refractive index barrier is wider than the result of SRIM2003.

Formation of Optical Waveguide and Annealing Behaviour of LiNbO3Implanted by 3.0-MeV Nickel Ions

The optically polished LiNbO3 crystal was implanted with 3.0 MeV nickel ions to a dose of 8×1014 ions/cm2. The implanted sample was orderly annealed at different temperatures for different times in air ambient. The waveguide properties before and after annealing were investigated. Dark modes were observed by the prism coupling technique. The reconstructed refractive index profiles were obtained with the reflectivity calculation method. With the fibre probe technique, the attenuation of the Ni-implanted barrier-confined waveguide was measured for the first time. The waveguide loss was reduced from 1.65 dB/cm to 1.19 dB/cm when annealing was at 300 degrees C for 30 min. With the annealing temperature increasing to 370 degrees C, only fewer broad dark modes were found. It is indicated that the lattice damage by implantation began to resume under this annealing condition. After annealing at 380 degrees C for 60 min, all the dark modes disappeared.