Fabrication and characterization of high-damage resistance Zn-diffused MgO:PPLN ridge waveguides

Abstract:

This study investigates the fabrication process of zinc-diffused ridge waveguides in periodically poled magnesi-um-doped lithium niobate (PPMgO:LN). A controlled variable method is used to study the effects of diffusion tem-perature, diffusion time, ZnO film thickness, and barrier layer thickness on the surface domain depolarization and waveguide quality of PPMgO:LN. A special barrier layer is proposed that can automatically lift off from the sample surface, which increases the depth of zinc doping and reduces the surface loss of the waveguide. By optimizing the process parameters, we fabricate zinc-diffused PPMgO:LN ridge waveguides with a length of 22.80 mm and a period of 18.0 μm. The above waveguides generate a second harmonic (SHG) at 775 nm with an output power of 90.20 mW by a pump power of 741 mW at 1550 nm. The corresponding conversion efficiency is 3.160%/W∙cm2, and the wave-guide loss is approximately 0.81 dB/cm. These results demonstrate that high-efficiency devices can be obtained through the fabrication process described in this paper.

Key words:periodically poled lithium niobate; Zn-diffusion; surface polarization domain depolarization; ridge waveguide; self lift-off