Polarizer

overview

overview

 FOCtek manufactures a wide range of polarizers (Glan Laser, Glan Taylor, Glan Thompson, Wollaston and Rochon) by employing birefringent crystals: a -BBO, Calcite, YVO4 and quartz. The material properties of birefringent crystals are great influence on your selection of right type polarizers.

  a -BBO (high temperature phase of BaB2O4) is characterized by large birefringent coefficient and wide transmission window from 189nm to 3500nm, particularly suitable for high power UV polarizer (200-300nm).   YVO4 crystal has been widely used in fiber optical components due to its large birefringence, good physical and favorable mechanical properties. Since the crystal has high transmission from 500 to 3500 nm, it is recommended to use YVO4 polarizer for IR (up to 4000nm) online_ordering.   Crystal quartz is a natural occurring as well as synthetically grown positive uniaxial crystal that is optical active, i.e. it rotates the plane of polarization of linearly polarized input beam traveling along the crystal optic axis. Because of it's reatively low birefringence, it is not feasible to fabricate a crystal quartz Glan type polarizer but as Rochon polarizer.   Calcite is a natural minded crystal and the most common crystals for polarizers used as visible and near IR polarizers. Defect in bulk calcite are characterized by bubbles, striae, optical inhomogeneity and stress birefringence. These defects cause degradation of polarization and transmission loss due to scattering and absorption. That is why the extinction of the polarizer is not as high as synthetically grown material YVO4, a -BBO and crystal quartz.

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