Fiber with metal coating News Our portfolio of specialty optical fiber is also available with Gold or Aluminum coating.Graded index or Step index Multimode and Singlemode designs can be combined with high temperature protection through the metal coating.You can read more about this product here: Singlemode Fibers: Metal Coated Series: Gold/AluminumGraded Index Multimode Fibers: Metal Coated Series: Gold/AluminumStep Index Multimode Fibers: Metal Coated Series: GoldStep Index Multimode Fibers: Metal Coated Series: Aluminum.