Photonic microstructures in lithium niobate by potassium hydroxide-assisted ion beam-enhanced etching

Lithium niobate is treated with argon ion beam irradiation of varying energy, resulting in a homogeneously damaged surface layer. This layer is subsequently etched with potassium hydroxide (KOH), and etch rates are recorded for different experimental conditions such as varying temperature and concentration of the water-based KOH solution. The dependence of the etch rate upon the normalized fluence of the ion irradiation shows good selectivity, which makes the effect useful for nano- and microfabrication. Ultimately, photonic crystals and gratings are fabricated by KOH-assisted ion beam-enhanced etching to prove the potential of this method for applications in functional nano- and micro-optics.