SYNTHETIC PROUSTITE (Ag3AsS3): A NEW CRYSTAL FOR OPTICAL MIXING

Proustite (Ag₃AsS₃), a new acentric crystal for optical mixing, has been synthesized as large transparent single crystals. It is uniaxial, having point group symmetry 3m. Proustite transmits from 0.6 to 13 μm, and has a large negative birefringence (n₀ − n_E ∼ 0.2). Using second‐harmonic generation from a 1.152‐μm laser, we estimate the nonlinear coefficients to be ${\mathrm{|d}}_{22}^{\mathrm{P}}{\text{|=50|d}}_{36}^{\mathrm{KDP}}|$ and ${\mathrm{|d}}_{31}^{\mathrm{P}}{\text{|=30|d}}_{36}^{\mathrm{KDP}}|$ . New optical mixing possibilities arise from the exceptionally wide range of processes that can be phase‐matched and the large nonlinear coefficients.