A preparation method of lithium niobate ridge optical waveguide

Abstract

The invention discloses a preparation method of a lithium niobate ridge-type optical waveguide. The preparation method comprises the following steps of: selecting an optical-grade Z-cut 0.35mm-thick lithium niobate wafer with the same component as a substrate, and carrying out light proton exchange for nearly 20 hours at 240 DEG C to prepare a planar waveguide, wherein a proton source adopts a mixture of benzoic acid and lithium benzoate; preparing a SiO2 mask with the strip width of nearly 2-4 microns and the thickness of nearly 100-200nm on the planar waveguide on the + Z surface by adoptingultraviolet lithography; carrying out proton exchange on the wafer with the mask for nearly 1 hour at 240 DEG C, wherein the thickness of an obtained exchange layer is nearly 0.7 micron, and the proton source is pure benzoic acid; and carrying out wet etching for nearly 4 hours at room temperature, and completely etching the proton exchange layer to obtain an etched ridge with the height of nearly 0.7 micron, wherein an etching solution adopts an HF-HNO3 mixed solution with the volume ratio of HF to HNO3 being 1: 3. The ridge-type optical waveguide prepared by the preparation method disclosedby the invention has the advantages of smooth surface, low loss and high quality; a high-temperature annealing link is avoided, and the crystal orientation structure of a waveguide area is better reserved; and the whole process link is less, the difficulty is relatively low, and the manufacturing cost is reduced.

Description

Technical field[0001]The invention relates to the field of integrated optoelectronics, in particular to a method for preparing a lithium niobate ridge optical waveguide.Background technique[0002]Lithium niobate crystal is one of the most excellent integrated optical materials. Using very mature titanium diffusion and proton exchange technology, integrated optical devices such as modulators, switches and switch arrays, optocouplers have been successfully developed, and a large number of applications have been obtained. High-speed lithium niobate modulators are important devices in high-speed optical communication systems. In order to improve its modulation bandwidth and better adapt to high frequency work, LiNbO3Ridge waveguides have been extensively studied.[0003]LiNbO3The production of ridge waveguides usually uses dry etching, such as plasma beam etching, radio frequency sputtering etching, reactive ion etching, and so on. In 1974, Kaminow et al. prepared a ridge waveguide phase m...

AI Technical Summary

Problems solved by technology

This method only avoids the problem of using a high temperature above 800°C, but the APE process will still destroy the crystal structure of the waveguide area, and cannot be applied to PPLN and other materials to make waveguides

Moreover, this method requires secondary photolithography alignment, which increases the difficulty of the overall process

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