Xianbing Ming

Theoretical modeling and experiment of refractive index change in He + ion-implanted KTP waveguide

A theoretical model is presented to explain the refractive index change in the ion-implanted KTP waveguide, which includes respective contributions of spontaneous polarization, molar polarization and molar volume, and photoelastic effect. Numerical calculations of refractive indices along different crystalline orientations (X, Y, and Z) as a function of the lattice damage level, determined by Rutherford back-scattering/channeling technique, are performed based on the results from a set of z-cut KTP crystals implanted by 300 keV He+ ions in doses ranging from 4×10(16) to 8×10(16) ions/cm2. The theoretical results show consistency with the experimental data. To our knowledge, this is the first model to comprehensively describe the ion-implanted KTP planar waveguide.

Formation and characterization of ZnO : Tm+ optical waveguides fabricated by Tm+ and O+ ion implantation

Planar optical waveguides were formed in ZnO crystal by Tm+ and O+ ion implantation. The distributions of Tm+ in as-implanted and annealed ZnO samples were investigated by the RBS technique. A shift of the Tm+ peak towards the sample surface and out diffusion were observed after thermal treatment and subsequent O+ ion implantation. Waveguide formation was determined after O+ implantation in Tm+-implanted ZnO crystal. By using the prism-coupling method two guided modes were detected. The refractive index profile in the implanted waveguide was reconstructed according to the SRIM and RCM simulation. The RBS/channelling measurements show that the lattice structure of ZnO did not suffer detectable damage after O+ implantation.

Optical confinement achieved in ZnO crystal by O + ions implantation: analysis of waveguide formation and properties

Optical confinement in ZnO crystal was observed by O(+) implantation with different MeV energies and doses. Planar optical waveguides were formed in the as-implanted ZnO samples. The optical properties of the planar waveguide were investigated by the prism-coupling and the end-face coupling methods at the wavelength of 633 nm. The crystal lattice damage in the guiding region caused by the O(+) ions implantation was analyzed by the Rutherford backscattering/Channeling technique, results show that even high dose at 2 × 10(15) ions/cm(2) can hardly produce defect in near surface of ZnO. A theoretical model is developed to explain the principle of waveguide formation in ZnO crystal and the refractive index profile in the implanted waveguide was reconstructed accordingly. The experimental result and analysis are significant for application of ZnO crystal, especially for the design of ZnO light emitter devices.

Theoretical modeling of refractive index in ion implanted LiNbO3 waveguides

A theoretical model is developed to evaluate the roles of various mechanisms, including the molar polarization and molar volume, the spontaneous polarization and the photoelastic effect, for the modifications of refractive indices in ion-implanted LiNbO3 waveguides. Based on the model, numerical calculations of refractive indices as a function of the lattice damage level in LiNbO3 crystals of different crystalline orientations (X, Y, and Z), are performed, with results in a good agreement with experimental data. The analysis indicates that the spontaneous polarization, the molar polarization, and molar volume play important roles in determining the index profiles in ion implanted LiNbO3. In addition, the contribution of the strain-induced photoelastic effect has been identified for different damage levels.

Analysis of Si + -implanted Nd:YVO 4 crystal: the relation between lattice damage and waveguide formation

We report the lattice damage and annealing properties of the 500 keV Si+ ions implanted Nd:YVO4 crystal with different doses. The Rutherford backscattering spectrometry/channeling technique was used to analyze the damage profiles of ion-implanted samples. A series of post-implant annealing was performed at temperatures from 250 °C to 400 °C to investigate the relation between lattice damage profile and the waveguide formation. Implantations at doses of more than 5×10(14) ions/cm2 can result in high damage ratio in the near-surface region and the lattice structure cannot be restored even after annealing at 400 °C. Such seriously damaged lattice is relatively stable and contributes to the waveguide structure. Convergence of the refractive index at the surface region after ion implantation is believed mainly due to the elastic collisions with the target atoms caused by nuclear energy loss.

The Damage Analysis of Nd:YVO4 Crystal Implanted by He+ Ions at Low Energy

We report the damage properties of the He⁺ ions implanted Nd:YVO₄ crystal. Implantation was carried out at room temperature by He+ ions at the doses of 1×10¹⁶, 2×10¹⁶, and 4×10¹⁶ ions/cm² with the energy of 200keV. The depth of the damage region is about 0.85μm beneath the surface. Rutherford backscattering spectrometry (RBS)/channeling technique was used to investigate the damage profile of ions implanted samples. Low atomic displacement ratio in as-implanted samples indicates a high irradiative resistance of YVO₄ crystal and the dynamic annealing effect of He⁺ ions in the implantation process. Post-implant annealing was performed for all the samples at 200°C and 300°C for an hour, respectively. The height and width of damage peak decreased somewhat after annealing at 200°C. Repairing and re-crystallization of damaged lattice was achieved after annealing at 300°C. Photoluminescence of ion-implanted samples were measured to investigate effect of implantation on fluorescence properties of Nd³⁺. The damage on sample surface was analyzed by optical microscopy (OM) and atomic force microscopy (AFM).