Xue-Lin Wang

Optical waveguides formed in Nd:YVO4 by MeV Si+ implantation

The planar waveguide has been fabricated in a Nd:YVO4 crystal by 3.0 MeV Si+ ion implantation at a dose of 1×1015 ions/cm2 at room temperature. The waveguide was characterized by the prism-coupling method. The dark modes are measured before and after the annealing at 240 °C for 60 min in air. The refractive index profile is reconstructed using reflectivity calculation method. It is found that relatively large positive change of ordinary refractive index happens in the guiding region, which is quite different from most of the observed ion-implanted waveguides. The TRIM’98 code is carried out to simulate the energy loss during the implantation in order to obtain a better understanding for the waveguide formation.

Formation of c-axis oriented ZnO optical waveguides by radio-frequency magnetron sputtering

ZnO/Mg0.16Zn0.84O (ZnO/MgZnO) films are fabricated on x-cut and z-cut LiNbO3 (LN) substrates by radio-frequency magnetron sputtering. High transparencies are confirmed by a spectrophotometer. X-ray diffraction (XRD) spectra show that all the films are c-axis oriented. The waveguiding properties, as well as the refractive indices and thickness of the films are demonstrated and determined by prism coupling. Both transverse electric (TE) and transverse magnetic (TM) modes are measured at lambda=0.633 mum and 1.539 mum, respectively. The waveguide loss is measured at lambda=0.633 mum with a fiber probe technique. The experimental results show that high optical quality ZnO films can be obtained with MgZnO buffer layers.

Optical properties of stoichiometric LiNbO3 waveguides formed by low-dose oxygen ion implantation

The planar waveguides in z-cut stoichiometric LiNbO3 crystal have been fabricated by 3.0 MeV oxygen ion implantation with the dose of 6×1014ions∕cm2 at room temperature. The modes of the waveguides were measured by the prism-coupling method with the wavelength 633 and 1539 nm, respectively. The refractive index profiles of the waveguides were reconstructed using reflectivity calculation method. The Rutherford backscattering/channeling technique was used to investigate the damage produced by the ion implantation, the minimum yield of the spectra was 4.52%. The propagation loss of waveguide was 0.61 dB/cm obtained by fiber probe technique. It was found that positive changes of extraordinary refractive indices happened in the guiding regions, and such change increased after the annealing treatment at 260 °C for 60 min.

Optical channel waveguides in Nd:YVO4 crystal produced by O+ ion implantation

In this letter, we report on optical channel waveguides in Nd:YVO4 crystals produced by photographic masking and following direct O+ ion implantation at 3.0MeV. Annealing treatments of the samples are performed to improve the waveguide stability and to reduce losses. An increase of the ordinary refractive index induced by the implantation is believed to be responsible for waveguide formation. Quasi-TM guided modes are observed, while no quasi-TE ones are detected. The optical damping coefficients are of 0.43, 0.63, and 0.54cm−1 for channel waveguides with widths of 4, 5, and 6μm, respectively. The result of modal analysis is in agreement with the experimental data.

Low-loss planar and stripe waveguides in Nd3+-doped silicate glass produced by oxygen-ion implantation

We report on the fabrication and characterization of low-loss planar and stripe waveguides in a Nd3+-doped glass by 6MeV oxygen-ion implantation at a dose of 1×1015ions∕cm2. The dark mode spectroscopy of the planar waveguide was measured using a prism coupling arrangement. The refractive index profile of the planar waveguide was reconstructed from a code based on the reflectivity calculation method. The results indicate that a refractive index enhanced region as well as an optical barrier have been created after the ion beam processing. The near-field mode profiles of the stripe waveguide were obtained by an end-fire coupling arrangement, by which three quasitransverse electric modes were observed. After annealing, the propagation losses of the planar and stripe waveguides were reduced to be ∼0.5 and ∼1.8dB∕cm, respectively.

Monomode optical waveguide excited at 1540 nm in LiNbO(3) formed by MeV carbon ion implantation at low doses.

The monomode enhanced-index LiNbO(3) waveguide excited at 1540 nm is reported. X-cut LiNbO(3) crystals were implanted at room temperature by 6.0 MeV C(3+) ions with a dose of 2.0x10(15) ions/cm(2). Low loss planar optical waveguides were obtained and characterized by the prism coupling technique. Four dark modes were observed for extraordinary light at 633 nm, while only one enhanced-index mode was observed at 1540 nm. The propagation loss of the waveguide is 1.01 dB/cm measured with the moving fiber method. Reflectivity calculation method (RCM) was applied to simulate the refractive index profiles in waveguide. The width of waveguide structure induced by carbon ion implantation is ~3.6 microm.

Planar optical waveguides in β-BaB2O4 produced by oxygen ion implantation at low doses

The planar waveguides have been fabricated in z-cut β-BaB2O4 crystal by 2.2MeV O+ ion implantation at doses ranging from 5×1012 to 5×1014ions∕cm2 at room temperature. The waveguides were characterized by the prism-coupling method. Monomode, nonleaky planar waveguides at λ=633nm in β-BBO single crystals were fabricated at doses from 5×1012 to 2×1013ions∕cm2, and two mode and three mode waveguides were fabricated at doses from 4×1013 to 5×1014ions∕cm2, respectively. The refractive index profiles of the waveguides are reconstructed using reflectivity calculation method. The propagation loss of the measured ion implanted waveguide was about 1.6dB∕cm. It was found that positive changes of extraordinary refractive indices happened in the guiding regions, and such changes increased with the doses, which were different from most of the observed ion-implanted waveguides.

Ion-implanted waveguides in Nd3+-doped silicate glass and Er3+/Yb3+ co-doped phosphate glass

The data are presented on the waveguides formation in the Nd 3þ -doped silicate glass and Er 3þ /Yb 3þ co-doped phosphate glass by the implantations of He þ or Si þ ions, respectively. The prism-coupling method is used to measure the effective refractive indices of the waveguide dark modes. The refractive index profiles of the waveguides are reconstructed by using the reflectivity calculation method (RCM) and a comparison of such profiles among the different waveguides has been made. The reasons for the formation of the present waveguides are analyzed in a primary way. # 2002 Elsevier Science B.V. All rights reserved.

Property investigation of C+-ion-implanted LiNbO3 planar optical waveguides

The LiNbO3 planar optical waveguides are fabricated by 3.0-MeV C+ ion implantation at the doses of 1.5–10.5×10(14)cm−2. Both TE and TM modes are observed by prism coupling method (m lines). The reconstructed refractive index profiles of the guiding region show that extraordinary index has an enhancement compared with the substrate of LiNbO3, while ordinary index experiences a typical “barrier” change. The modal analysis of the waveguides shows a good confinement of light in fundamental TM mode. The tendency of effective refractive index (decrease after the annealing for TE and increase after annealing for TM) suggests a moderate recovery of the lattice.

Low-loss optical planar waveguides in YVO4 produced by silicon ion implantation at low doses

Planar waveguides in x-cut YVO4 crystals were produced by ion-implanted Si+ ions with energies from 2.6 to 3.0 MeV at doses of 1×1013−1.5×1014 ions/cm2. The number of propagation modes varied from 1 to 3 as the doses of the implanted ions increased. The effective refractive indices of all the observed waveguide modes were higher than the refractive index of the substrate, which meant an index-enhanced guiding layer with thickness of ∼2 μm formed to confine the light propagation. The minimum propagation loss of the measured YVO4 waveguide was 0.27 dB/cm after annealing under suitable conditions.