Properties Of Proton-exchanged Waveguides Research Articles

The impact of various factors on the surface of X-cut lithium niobate and properties of proton-exchanged waveguides

This work describes the effects of various impacts (thermal, plasma, chemical) on X-cut lithium niobate surface and on the structure and optical characteristics of proton-exchanged waveguides. Pre-annealing at 500 °C improved the structural homogeneity of congruent lithium niobate and thus enabled fabricating waveguides of a higher quality. Ar-plasma pretreatment damaged crystal surface and increased lattice deformations. Chemical treatment influenced the surface composition of lithium niobate and the refractive index in annealed proton exchange waveguides. The results provide better understanding of the role of crystal surface in the fabrication of diffusion waveguides and photonic integrated circuits.

Influence of surface treatment on the structure and properties of proton-exchanged waveguides in lithium niobate

The influence of reverse proton exchange (RPE) and some types of surface pretreatment (exposure to Piranha or RCA-1 solutions or to HNO3+HF mixture) on the structure and properties of proton-exchanged layers has been studied in X-cut lithium niobate (LN). It has been shown that the rate of phase transitions in PE layers during RPE is greater than that during annealing at the same temperature. Pretreatment of LN surface before PE by Piranha or RCA-1 solutions slightly increases refractive index change Δne in the resulting waveguide, whereas pretreatment by HNO3+HF mixture decreases it.