Regular domain structures on the Y cuts of the LiNbO3 substrates and Ti:LiNbO3waveguide structures based on these substrates have been fabricated under electron-beam irradiation. It has been...

In this review, our recent results on the electron-beam domain writing (EBDW) on the nonpolar surfaces of LiNbO₃ crystals of different compositions are presented. Under EB irradiation of the nonpolar surfaces, domains nucleated in irradiation points grow frontally along the polar [Formula: see text]-direction in a thin (of microns in thickness) surface layer; the driving force is the tangential component of space-charge fields induced by EB in irradiation points. This geometry of the experiment provides a possibility of three-dimensional (3D) characterization of domain patterns using the combination of atomic force microscopy (AFM) and second harmonic generation (SHG) confocal microscopy methods. The obtained results permitted us to relate the main characteristics of domain formation (the domain sizes and velocity [Formula: see text] of the frontal motion) to the irradiation conditions (the accelerating voltage [Formula: see text] of scanning electron microscopy (SEM), EB current [Formula: see text], the inserted charge [Formula: see text]). The domain depth [Formula: see text] is controlled by [Formula: see text] via the electron penetration depth; the domain length [Formula: see text] increases linearly with [Formula: see text] owing to the domain frontal growth by the viscous friction law. The electron emission coefficient [Formula: see text] affects the domain formation due to the fundamental dependence of [Formula: see text] on [Formula: see text]. In the framework of current approach to EB charging of insulators, the effect of an enhanced conductance on EBDW characteristics is analyzed. The difference between EBDW characteristics observed in varied LiNbO₃ compositions is discussed in the framework of the intrinsic defect structure of LiNbO₃. The obtained results extend the possibility of EBDW application to a wider range of crystals.

We present the results of studies in planar optical waveguides fabricated by He-ion implantation with the energy of 500 keV in X-cut LiNbO ₃ crystals. The thickness of the formed waveguide layer confined by the depth D of the implanted layer is of about 1.06 μm. The refractive indices as well as differences in refractive indices were evaluated for wavelengths λ = 445, 626.5, and 650 nm. Domain gratings with the period λ = 4 μm were recorded in these samples by electron beam irradiation with acceleration voltages U in the range from 5 to 25 kV. Gratings characteristics measured by the PFM method were obtained for different domain thicknesses T _d determined by U. The optimum grating regularity is achieved when the domain growth occurs beyond the He-implanted damaged barrier, i.e., at T _d ≤ D, which in the given case corresponds to U = 10 and 15 kV. Otherwise, (T _d > D), the domain evolution is affected by the structurally damaged layer and the gratings become irregular.