Achromatic-zero-order-waveplates are high-stability broadband polarization phase retardation elements, combining zero-order retardation stability and achromatic dispersion compensation. They are usually composed of two complementary birefringent materials (such as quartz and magnesium fluoride MgF₂) with orthogonal optical axes, which can maintain a fixed phase retardation (λ/4 or λ/2) in a wide wavelength range, and have extremely low sensitivity to wavelength, temperature and incident angle. They are widely used in high-precision polarization modulation, broadband optical systems and laser applications.
