Periodically Poled Lithium Niobate: Modeling, Fabrication, and Nonlinear-Optical Performance


Periodically poled lithium niobate (PPLN) has become the nonlinear-optical material of choice in many infrared optical parametric oscillators (OPO's) due to its high nonlinearity, readily engineered tuning characteristics, and repeatable fabrication. The domain periods required for these OPO's are typically between 15 um and 30 um, and are made by a process already well developed. The domain periods required for visible light applications are typically between 3 um and 10 um, and are more difficult to fabricate repeatably. The focus of this research was to understand the nature of this difficulty, to develop strategies for repeatable device fabrication, and to demonstrate the nonlinear optical performance of the material.

This thesis presents a model of the periodic-poling process in lithium niobate, a repeatable PPLN-fabrication process developed using this model, and the nonlinear-optical performance of PPLN fabricated with this process. The model combines ferroelectric properties of the material, measured as part of this research, with the electrostatics of periodic electrodes. The fabrication process developed using the model was used to periodically pole two 75-mm-diameter wafers of 500-um-thick LiNbO3 with a 6.5 um domain period. These wafers yielded 53-mm-long samples, more than five times the length previously reported. Second harmonic generation experiments performed with these samples produced 2.7 watts of 532 nm radiation output with 6.5 watts of continuous-wave 1064 nm Nd:YAG laser radiation input, corresponding to a record 42% single-pass conversion efficiency. These samples were also used to operate the first reported continuous-wave 532-nm-pumped PPLN-based singly-resonant OPO, with a record-low 0.93-watt threshold (relative to other 532-nm-pumped OPO's), 56% conversion efficiency, and continuous tuning from 917-1266 nm. Finally, data are presented that indicate the presence of 532-nm-induced 1064-nm absorption.


Gregory David Miller


July, 1998