Nonlinear Optical Properties of Hexagonal Silicon Carbide

Optical second harmonic coefficients, refractive indices, and optical transmission of hexagonal SiC have been measured at room temperature. The nonlinear coefficients measured relative to quartz for a 1.064‐μm fundamental are $d_{15}^{\mathrm{SiC}}{\text{=(25± 3)d}}_{11}^{\mathrm{\alpha \; -}{\mathrm{SiO}}_2}$ , $d_{31}^{\mathrm{SiC}}{\text{=(27± 3)d}}_{11}^{\mathrm{\alpha \; -}{\mathrm{SiO}}_2}$ , and $d_{33}^{\mathrm{SiC}}{\text{=(45± 5)d}}_{11}^{\mathrm{\alpha \; -}{\mathrm{SiO}}_2}$ . The observed Miller δ coefficients are in poor agreement with the values calculated from Levine's bond‐charge model. Type‐II phase matching should be achievable with SiC for fundamental wavelengths greater than 2.0 μm.