We report on the fabrication of ion-sliced single-crystalline lithium niobate thin films and realization of electro-optically tunable microring resonators and photonic bandgap structures for high-density integrated optics devices. Using a home-built high-resolution laser lithography system we structured microring resonators with a free spectral range of > 7 nm, a quality factor of up to 10'000, and a tunability of 1 pm/V at wavelengths around 1.55 mu m. Moreover, we show that the fabricated microrings can be detached from the original substrate and transferred onto any host substrate. This opens new possibilities for building hybrid integrated optics devices based on lithium niobate microrings and laterally or vertically coupled waveguides of different materials. Combining the laser lithography patterning and focused ion beam milling we have also fabricated planar photonic crystals structures. Triangular lattices of holes with a diameter of 240 nm and a separation of 500 nm exhibit a photonic bandgap in the wavelength range from 1390 and 1500 nm with an extinction ratio of up to 15 dB.

We report on the fabrication of free-standing microrings using ion-sliced lithium niobate thin films bonded by benzocyclobutene on a lithium niobate substrate. The microrings can be detached from the benzocyclobutene layer using standard clean-1 solution and transferred onto any host substrate. This approach is suitable for building hybrid integrated optics devices with laterally and vertically coupled lithium niobate microring resonators. Gallium nitride was identified as a suitable material for the port waveguides in such a device due to the refractive index similar to lithium niobate. In our study, we transferred lithium niobate microrings on top of gallium nitride waveguides and aligned them for vertical coupling using a micropositioning tool. Transverse-electric-wave transmission spectra of the microring resonators with a radius of 20 ¿m exhibited a free spectral range of 8.1 nm and a finesse of ~ 23 at 1.55- ¿m wavelength. The resonance dips in these spectra showed an extinction ratio of up to 12 dB.

We report on the realization of electro-optically tunable microring resonators and photonic crystal structures in ion-sliced lithium niobate thin films. The fabricated microresonators exhibit FSR > 7 nm, Q ≈ 10’000, and a tunability of 1 pm/V. Our novel technique enables also the fabrication of free-standing lithium niobate microrings suitable for hybrid optical integration. Combining laser lithography and focused ion beam milling we realized photonic bandgap structures exhibiting an extinction ratio of up to 15 dB at wavelengths around 1500 nm.

This article present the fabrication of compact electro-optically tunable microring resonators in lithium niobate and discuss their performance in the telecommunication wavelength range around 1.55 mum.

In these studies, annealed proton exchanged waveguides were used to confine the light to two dimensions and the photonic bandgap structures were fabricated by focused ion beam milling. These planar waveguides have a thickness of about 2 microns and a rather low refractive index contrast with respect to the bulk crystal, thus a high aspect ratio of air holes is required. In our approach we use 600-nm thick ion-sliced LiNbO 3 films bonded to a LiNbO 3 handling substrate using an adhesive polymer. Such LiNbO 3 films enable substantially stronger optical confinement and are ideally suited for the fabrication of photonic crystal slabs.

We report on the first realization of photonic crystal structures in 600-nm thick ion-sliced, single-crystalline lithium niobate thin films bonded on a lithium niobate substrate using adhesive polymer benzocyclobutene (BCB). Focused ion beam (FIB) milling is used for fast prototyping of photonic crystal structures with regular cylindrical holes. Unwanted redeposition effects leading to conically shaped holes in lithium niobate are minimized due to the soft BCB layer underneath. A high refractive index contrast of 0.65 between the lithium niobate thin film and the BCB underlayer enables strong light confinement in the vertical direction. For TE polarized light a triangular photonic crystal lattice of air holes with a diameter of 240 nm and a separation of 500 nm has a photonic bandgap in the wavelength range from 1390 to 1500 nm. Experimentally measured transmission spectra show a spectral power dip for the GK direction of the reci ocal lattice with an extinction ratio of up to 15 dB. This is in good agreement with numerical simulations based on the three-dimensional plane wave expansion (PWE) and the finite-difference time-domain (FDTD) method.

We report on sub-micrometer thick LiNbO3 films produced by an improved crystal ion slicing and bonding technique using polymer adhesive benzocyclobutene. The latter enables to reproducibly fabricate defect-free films with an area of several cm2. The method supports also integration of tuning electrodes enabling realization of complex electro-optically active photonic devices on a single chip. Furthermore, the structuring techniques to produce high-index-contrast (Δn≈0.65) single-mode optical waveguides are described. The big potential of the novel LiNbO3 thin films for high-density integrated optics applications is shown on an example of electro-optically tunable microring resonator.

We report on the second harmonic generation of deep UV light in beta -BaB(2)O(4) (BBO) waveguides pumped by a frequency-doubled continuous-wave Nd:YAG laser. An output power of 0.32 mW at 266 nm has been achieved for an internal pump power of 670 mW. Optical channel waveguides in BBO crystals were produced by He(+) ion implantation, lithographic masking and ion etching. The linear and nonlinear optical properties and the power handling capability of these waveguides are presented.