Calligraphic poling for WGM resonators

By engineering the geometry of a nonlinear optical crystal, the effective efficiency of all nonlinear optical oscillations can be increased dramatically. Specifically, sphere and disk shaped crystal resonators have been used to demonstrate nonlinear optical oscillations at sub-miliwatt input power when cw light propagates in a Whispering Gallery Mode (WGM) of such a resonant cavity. In terms of both device production and experimentation in quantum optics, some nonlinear optical effects with naturally high efficiency can occult the desired nonlinear scattering process. The efficiency of second order nonlinear optical effects in ferroelectric crystals can be increased by engineering a poling structure to the crystal resonator. In this paper, I will discuss a new method for generating poling structures in ferroelectric crystal resonators called calligraphic poling. The details of the poling apparatus, experimental results, and speculation on future applications will be discussed.