Effects of Domain Disorder in QPM Devices

QPM based on periodically poled ferroelectrics have enjoyed widespread use due to the ability to engineer a device for a particular nonlinear interaction of interest. Random duty cycle errors are inherent in production of QPM gratings by periodic poling as domains spread out slightly unevenly from poling electrodes. We have imaged domain disorder in our own PPLN devices (a) to quantify their severity: a histogram of domain size in a typical device is shown in (b). We have analytically and numerically investigated the effects of domain disorder on device performance and have found that a QPM pedestal results that can enhance the efficiency of unwanted parasitic processes that would ordinarily not be phasematched. Future work will address higher-order moments of the domain size statistics and their effect on fluctuations in the phasematching pedestal. With additional research, we hope to learn how to minimize random duty-cycle errors during the poling process, thereby reducing their effects in QPM applications.