Dry etching of LiNbO<inf>3</inf> using inductively coupled plasma

In this letter, we report ridge waveguides fabricated on X-cut proton exchange (PE)-LiNbO ₃ using inductively coupled plasma (ICP) etching techniques. Various etching masks and fluorine gases are investigated. Smooth etched surfaces are obtained by using Cr as a mask combined with SF ₆ /Ar etching gases. A high etch rate of 97.5 nm/min is achieved by using CHF ₃ /Ar gases. Ridge waveguides with approximately 600nm depth, smooth surfaces and nearly vertical sidewalls are successfully fabricated using optimized etching conditions.