Nanometer size periodic domain inversion in LiNbO3 substrate using circular form full cover electrodes

We have proposed circular form full cover electrodes (CF-FCE) for nanometer size periodic domain inversion in LiNbO3 (LN) substrate. From the calculated results, circular form electrode is better than that of rectangular type for fine domain inversion patterns. Circular form FCE were fabricated over the photoresist patterned by two-beam laser interference exposure method. Domain inversion was performed by applying high voltage to circular form FCE. Using this technique, we successfully fabricated 2 μm periodic domain inversion in a 500 μm-thick congruent LN (C-LN) crystal. It is also shown that smaller domain inversion width in the nanometer regime with high aspect ratio is possible using this technique. We obtained an aspect ratio as high as 870 for a domain inversion width of 575 nm. To our knowledge, such a high aspect ratio is reported for the first time.