Three crystals for optical use include a birefringent crystal a-BBO, with refractive indices of no=1.67 and ne=1.53 in the visible, which acts birefringent throughout its transmissive range from 189 to 3500 nm. Applications include polarizers, fiber isolators, and walk-off beamsplitters. Nonlinear-crystal, strontium-doped b-BBO, can offer more efficient second- and third-harmonic conversion of Nd:YAG light than BBO. For passively Q-switching lasers at wavelengths from 1 to 1.2 µm, Cr-doped YAG crystals are available with custom coatings.
Casix, Fuzhou, Fujian, China