Finding the Next Deep-Ultraviolet Nonlinear Optical Material: NH₄B₄O₆F

TLDR

Nonlinear optical materials are essential for solid‑state lasers, yet the only deep‑UV material KBBF has limited industrial use. The study reports a new material, NH4B4O6F, that enables deep‑UV frequency doubling below 200 nm. The authors synthesized NH4B4O6F crystals with a wide deep‑UV transparency range and birefringence suitable for sub‑200 nm frequency doubling. NH4B4O6F has nonlinear coefficients ~2.5 × that of KBBF, is easy to grow in bulk, and contains no toxic elements.

Abstract

Nonlinear optical materials are essential for the development of solid-state lasers. KBe2BO3F2 (KBBF) is a unique nonlinear optical material for generation of deep-ultraviolet coherent light; however, its industrial application is limited. Here, we report a new material NH4B4O6F, which exhibits a wide deep-ultraviolet transparent range and suitable birefringence that enables frequency doubling below 200 nm. NH4B4O6F possesses large nonlinear coefficients about 2.5 times that of KBBF. In addition, it is easy to grow bulk crystals and does not contain toxic elements.