Spherical ball lenses are commonly used for laser collimating and focusing, laser-to-fiber coupling, fiber-to-fiber coupling, and fiber-to-detector coupling. Four diameters are available — 1, 2, 3, and 5 mm. Larger spheres are easier to handle and ease the sensitivity of translational alignment. However, smaller spheres fit into smaller packages.
The addition of broadband MgF2 antireflection coating centered at 830, 1300, or 1500 nm results in a highly efficient lens due to the high refractive index of the glass.
Coupling efficiency is generally > 90% due to the simplicity of these lenses.
