We are developing the diffusion-bonded stacked (DBS) structure for quasi-phasematched interactions to meet the need for high- power nonlinear conversions in the infrared. In our preliminary investigations, we have compared optical and thermal properties of some potential DBS materials. Theoretical projections of device performance were compared for DBS GaAs and ZnSe and birefringent crystals ZnGeP2 and AgGaSe2 for both second- harmonic generation (SHG) of 10-micrometers radiation and 2-micrometers pumped optical parametric oscillators (OPOs). We are refining bonding processes for GaAs and have initial diffusion bonding results for ZnSe. We have fabricated and tested DBS GaAs structures for SHG, demonstrating that the crystal orientation is conserved during the bonding process, and that the nonlinear generation of the individual layers sums coherently. These studies indicate that DBS materials have potential for application in high-average-power OPOs.