γ-NaAsSe2: new infrared non-linear optical crystal with superior optical properties

The γ-NaAsSe2 has attracted much attention as the next-generation infrared (IR) nonlinear optical (NLO) crystal. It has demonstrated one of the highest second harmonic generation (SHG) efficiencies as polycrystal. However,the full optical properties of single crystal have not been studied yet, which is required to understand its potential for future IR laser applications. Here, its linear and nonlinear optical properties are examined using spectroscopic ellipsometry and optical second harmonic generation (SHG).