Feng-Xiang Wang

Optical waveguide formation by MeV H+ implanted into LiNbO3 crystal

Abstract A MeV H+ ion-implanted waveguide was formed on an LiNbO3 substrate. The dose of implanted H+ ions was 2×1016 ions/cm2 with an energy of 1.0 MeV at room temperature. The dark modes were measured using the prism coupling technique. The refractive index profile was analyzed using the reflectivity calculation method. The fiber probe technique was used to measure the attenuation of the waveguide. The lattice damage in the guide region caused by H+ ion implantation was investigated using the RBS/channeling technique.

Refractive index profiles of ion implanted waveguides in thulium sodium yttrium tungstate

Abstract Planar waveguides were first formed in thulium sodium yttrium tungstate (Tm:NaY(WO 4 ) 2 ) crystals by the implantation of MeV He, P and Ni ions with certain doses at room temperature, respectively. The refractive index profiles of the three ion implanted waveguides were found different to some extent. The present data show that He + ion implanted waveguides in Tm:NaY(WO 4 ) 2 should be the typical barrier type one, while a combination of radiation damage and radiation enhanced diffusion may be responsible for the refractive index profiles of the MeV Ni + and P + ion implanted waveguides in Tm:NaY(WO 4 ) 2 .

Refractive index profiles in LiNbO3 waveguide formed by 3.2 MeV He ions

Abstract Optically polished y-cut LiNbO 3 was implanted at 3×10 16 ions/cm 2 at room temperature. In order to minimize any channeling effects, the sample was implanted at 7° off the major symmetry axis. The He beam current was approximately 700 nA and the scanning area was 0.8 cm 2 . The prism coupling method was carried out to measure the dark modes in the LiNbO 3 waveguide. In the present work, an isosceles prism (rutile) was used. The dark modes were measured at 632.8 nm (He–Ne). Fifteen TM modes and 13 TE modes in the LiNbO 3 waveguide were observed. We have used the reflectivity calculation method (RCM) developed by Chandler and Lama to fit the refractive index profile. This method has been used for ion-implanted waveguides based on dark mode lines by the prism coupling method. Also we have used the TRIM (transport of ions in matter) code to simulate the damage profile in LiNbO 3 by 3.2 MeV He ions which is helpful for choosing the analytic function in RCM calculations.

Channeling study of proton-exchanged LiNbO3 optical waveguides

The disorder profiles of Nb atoms in proton-exchanged X- and Z-cut LiNbO 3 waveguides before and after annealing are obtained by Rutherford backscattering/channeling technique. Step-like disorder distributions are found in as-exchanged X-cut LiNbO 3 waveguide regions. An increasing trend of disorder ratio with depth appears in as-exchanged Z-cut LiNbO 3 waveguide regions. It is shown that the displacement of Nb atoms is larger along the c-axis than along the a-axis, After annealing, more than 70% of the total Nb atoms are in their original crystal lattice sites. The displacement of Nb atoms seems not to be the main reason for the decrease of the spontaneous polarization in proton-exchanged LiNbO 3 waveguides.

Electronic stopping powers of Au, Ag, Cu, Pd and Co metals for 19F ions at low velocity

Abstract Electronic stopping cross sections for 80–350 keV 19 F ions in Au, Ag, Cu, Pd and Co films were obtained by range measurement. Depth profiles of 19 F in these materials were measured by 19 F( p , αγ ) 16 O resonance nuclear reaction. A proper deconvolution program was used to extract the depth distribution parameters from the experimental excitation yield curves. The electronic stopping powers were derived through fitting the projected ranges simulated by TRIM/XLL code to the experimentally determined projected ranges. It is shown that the electronic stopping cross sections obtained in this work agree well with those calculated by using TRIM96 as well as previous experimental data and can be described by the four-parameter formulae.

Quantitative analysis of the oxygen content in BaTiO3 films deposited by PLD using 16O(α, α)16O resonant elastic scattering

The resonant elastic scattering 16O(α,α)16O at near 3.045 MeV is a very powerful tool for determining the oxygen concentration in oxide films. The resonance yield can be transformed into the stoichiometric ratio of oxygen to Ba–Ti as a function of the probed depth. By means of the resonance yield, we can obtain the oxygen concentration in BaTiO3 films. In this work the method was used to analyze the oxygen concentration of the BaTiO3 films deposited by pulsed laser deposition (PLD) at different oxygen ambience. Our experimental results demonstrate that the oxygen concentration in the films deposited by PLD is homogeneous, and the effect of oxygen pressure in the process of deposition on the oxygen concentration in the films is very significant. It is shown in our experiment that 20 Pa is the lowest value of oxygen pressure for forming optimum BaTiO3 films by the PLD method.

Range straggling and lateral spread of MeV Au+ ions in LiB3O5 and SiN1.375H0.603

Both LiB3O5and SiN1.375H0.603 were implanted by 1.0 MeV Au+ ions to a dose of 5×1015 ions cm-2 under different angles. The range straggling and lateral spread of 1.0 MeV Au+ ions in both LiB3 O5 and SiN1.375H0.603 were investigated by the Rutherford backscattering of 2.1 MeV He2+. The experimental mean projected range, range straggling and lateral spread are 279.7 nm, 54.0 nm and 34.6 nm for the case of LiB3O5, and 222.3 nm, 54.6 nm and 31.5 nm for the case of SiN1.375H0.603. The results show that the experimental range straggling and lateral spread are much larger than the values predicted by the 1998 version of the Transport of Ions in Matter code (TRIM98). After inelastic effects have been included in nuclear stopping regime, there is a much closer agreement with the experimental values than the original TRIM98 codes have. The maximum differences of the mean projected range, range straggling and lateral spread between experimental and calculated values are less than 3%, 24% and 21%, respectively for both cases.

Splitting Behaviour of Implanted MeV Au+ Ions in LiB3O5

The diffusion behaviour of 1.0 and 2.0 MeV Au+ implanted into LiB3O5 single crystal has been studied by the Rutherford backscattering of 2.1 MeV He ions. Annealing was performed at temperatures of 600, 700, and 800?C each for 30 min. The results show that the diffusion behaviour is quite different in two cases. In LiB3O5, the depth distribution of the 1.0 MeV Au is nearly Gaussian and becomes bimodal after annealing at 800?C for 30 min. But in the case of 2.0 MeV, the depth distribution of as implanted Au+ in LiB3O5 has splitting behaviour. After 800?C for 30 min annealing, there is no obvious diffusion observed. The precise interpretation is needed.