Hervé Tronche

Highly Confining Proton Exchanged Waveguides on Z-Cut LiNbO 3 With Preserved Nonlinear Coefficient

We propose a new proton exchange process to reproducibly realize on lithium niobate highly confining (δne = 0.1) planar waveguides without degrading the nonlinear coefficient of the crystal. Waveguides were fabricated with different acidic baths and the crystallographic changes, the index profiles and the local SHG response were measured. We show that for certain fabrication conditions, characteristic of the so-called high-index soft proton exchange process, the high-index modification can be obtained without degrading the crystal nonlinear coefficient. This result should open the way to the fabrication of very efficient nonlinear devices.

Soft-proton exchange on magnesium-oxide-doped substrates: A route toward efficient and power-resistant nonlinear converters

Despite their attractive features, integrated optical devices based on Congruent-melted Lithium Niobate (CLN) suffer from Photo-Refractive Damage (PRD). This light-induced refractive-index change hampers the use of CLN when high-power densities are in play, a typical regime in integrated optics. In bulk devices, the resistance to PRD can be largely improved by doping the lithium-niobate substrates with magnesium oxide. However, the fabrication of waveguides on MgO-doped substrates is not as straightforward as on CLN and either the resistance to PRD is strongly reduced by the waveguide fabrication process (as it happens in Ti-indiffused waveguides) or the nonlinear conversion efficiency is lowered (as it occurs in annealed-proton exchange). Here, we fabricate waveguides starting from MgO-doped substrates using the Soft-Proton Exchange (SPE) technique and we show that this combination represents a promising alternative. We demonstrate that, with a small adaptation of the exchange parameters, SPE allows prod...

Crystallographic and Optical Properties of Z-Cut High Index Soft Proton Exchange (HISoPE) LiNbO 3 Waveguides

Highly confining nonlinear optical waveguides are extremely interesting for highly efficient and ultracompact nonlinear and/or electro-optical devices. In this paper, we concentrate on correlations between structural and optical properties of channel waveguides on z-cut lithium niobate fabricated using a new waveguide fabrication method, we call HISoPE for high index soft proton exchange, which allows obtaining a guiding layer presenting an index increase as high as 0.1 and a nonlinear coefficient equal to its value in the bulk.