Jin-Hua Zhao

Lithium Niobate Ridge Waveguides Fabricated by Ion Implantation Followed by Ion Beam Etching

A new fabrication method for lithium niobate ridge waveguides is reported. Lithium niobate ridge waveguide with a smooth surface was fabricated by O+ ions implanted combined with Ar ion beam etching. The beam propagation method (BPM) was used to simulate the properties of planar and ridge waveguides by use of a reconstructed refractive index profile. The simulation results match to the experimental results very well, and the loss value of the ridge waveguide is about 2 dB/cm.

Optical properties of planar waveguides on ZnWO 4 formed by carbon and helium ion implantation and effects of annealing

We report on the optical properties of ZnWO(4) planar waveguides created by ion implantation, and the effect annealing has on these structures. Planar optical waveguides in ZnWO(4) crystals are fabricated by 5.0 MeV carbon ion implantation with a fluence of 1 × 10(15) ions/cm(2) or 500 keV helium ion implantation with the a fluence of 1 × 10(16) ions/cm(2). The thermal stability was investigated by 60 minute annealing cycles at different temperatures ranging from 260°C to 550°C in air. The guided modes were measured by a model 2010 prism coupler at wavelengths of 633 nm and 1539 nm. The reflectivity calculation method (RCM) was applied to simulate the refractive index profile in these waveguides. The near-field light intensity profiles were measured using the end-face coupling method. The absorption spectra show that the implantation processes have almost no influence on the visible band absorption.

Ridged LiNbO

We report on a new wet etching/ion implantation method for fabricating ridge waveguide on z -cut LiNbO3. The ridge structures are produced on LiNbO3 crystal by anisotropic wet etching via minus z face. Mode guiding at wavelength of 632.8 nm has been realized by using direct 4.5 MeV oxygen implantation without any implantation mask. The ridge waveguide shows a reduced propagation loss of 1.3 dB/cm after the thermal annealing process.

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We related the refractive index change in ion-implanted LiNbO3 crystals to the lattice damage ratio using a quadratic polynomial relationship. We used this relationship to calculate the refractive index profiles of z-cut LiNbO3 crystals implanted with oxygen ions using different energies, fluences, and annealing treatments. A highly damaged surface layer with a decreased refractive index was caused by electronic excitations in LiNbO3 crystals implanted with 4.0 MeV oxygen ions at a fluence of 2×1015 ions/cm2, which buried the optical modes inside the crystals. This relationship was also used for the estimation of the lattice damage in ion-implanted LiNbO3 crystals. It could make a quick estimate which was basically agree with the measured damage level.

Waveguide Fabricated By a Novel Wet Etching/MeV Oxygen Ion Implantation Method

We fabricated a single-mode planar waveguide in z-cut Nd:YVO(4) by multienergy He ion implantation in total fluence of 4.5×10(16) ions/cm(2) at room temperature and investigated optical properties of Nd:YVO(4) before and after He ion implantation by measuring transmission, confocal microluminescence, and confocal Raman spectra. Absorption bands and the photoluminescence features of the bulk Nd:YVO(4) crystal have been preserved after He ion implantation. In Raman spectra, most of the peak positions and peak widths had no obvious change before and after He ion implantation. The guiding mode and near-field image in the waveguide were measured by the prism coupling method and end-face coupling method, respectively. We investigated the damage behavior of a Nd:YVO(4) waveguide after implantation, annealing treatment by the Rutherford backscattering/channeling technique. The minimum yield of the virgin z-cut Nd:YVO(4) was 1.98%, which increased to 4.73% after He ion implantation and decreased to 3.20% after annealing at 600 K for 30 minutes.