A system and method for diamond based multilayer antireflective coating for optical windows are provided. An antireflective coatings for optical windows may include an optical grade silicon substrate; a plurality of polycrystalline diamond films, a plurality of germanium films, and a plurality of fused silica films. A method of fabricating a diamond based multilayer antireflective coating may include the steps of cleaning and seeding an optical substrate, forming a plurality of diamond layers above the optical substrate, forming a plurality of germanium layers above the optical substrate; and forming a plurality of fused silica layers above the optical substrate, wherein the reflectance of the antireflective coating is between 0.1 and 3.0 percent for infrared spectrum wavelengths between 1800 and 5000 nanometers.