Ferroelectric-domain-inverted gratings by electron beam on LiNbO3

In the field of integrated optics for WDM networks, periodically poled Ti:LiNbO3 seems to be an attractive candidate as it allows to build polarization-independent devices. A preliminary study about LiNbO3 without any Ti-indiffusion is presented here. Hence, a ferroelectric-inverted grating is achieved using electron beam (EB) on LiNbO3. In this study, the EB irradiation is performed with a scanning electron microscope (SEM) featuring a maximum accelerating voltage of 30 kV. A specific computer-aided design (CAD) application driving the SEM allows to write different structures such as periodic gratings. The EB domain-reversal method seems to be promising because of the accurate control and resolution of the reversed domains it can create. A pertinent choice: of the irradiation conditions (accelerating voltage, probe current, scanning velocity, etc.) permits to generate gratings with 6.6, 20 and 30 mum wide periods. The inversion patterns have been revealed by HF-etching: domain walls are perpendicular to the surface in the first microns beneath the surface and their depth is almost the whole thickness of the wafer. (C) 2001 Elsevier Science Ltd. All rights reserved.