Precise control of nanodomain size in LiNbO3

Abstract

It is still a gap to precisely control nanodomian size in ferroelectric nanoscale periodically poled structures, which is needed in nonlinear optics and quantum optics. In particular, when the lateral nanodomain size is comparable to the domain wall width in ferroelectrics, the optical properties of the domain or the electrical properties of the domain wall strongly depend on the lateral domain size, which is worthy to be noticed in nonlinear optical applications or domain wall electronics. However, the present experimental results about the nanodomian fabrication in widely-used lithium niobate crystal can not meet the need for precisely controlling nanodomian size, because high duty cycle, imprecise period or instability in domain structures fabricated by these techniques can not be ignored. In this paper we report on our experiment to precisely control the lateral nanodomain size in 1D PPMgLN. The SEM image shows that the average period and the standard deviation are 267 nm and 6 nm, respectively. The average duty cycle and the standard deviation are 52% and 2%, respectively. The depth of inverted domain is about 1.2 μm and meantime, the domain structure is stable within 30-day observation period. At last, we discuss the possibility to fabricate ultrahigh-Q Photonic crystal (PhC) cavities based upon our poling method. To the best of our knowledge, it is the first time to precisely control the lateral nanodomain size and reduce it down to near domain wall width in 1D PPMgLN.