Higher-order nonlinear dielectric microscopy

A higher-order nonlinear dielectric microscopy technique with higher lateral resolution than conventional nonlinear dielectric imaging is investigated. The proposed scheme involves the measurement of higher-order nonlinear dielectric constants, with sensitivity to the first 0.75 nm in depth for LiNbO3 substrate surface. This technique is demonstrated to be very useful for observing surface layers of the order of unit cell thickness on ferroelectric materials.