Abstract: The invention is a method of making fiber optic-to-metal connection seals. The optical fiber and a preform made of a sealing material are inserted into a metal cup. The metal is then heated to a temperature which melts the sealing material to form a hermetic seal between the cup and the fiber optic. The hermetic sealing material is selected from glass, glass-ceramic or braze and the metal is selected form stainless steel, a metal alloy or a high-strength superalloy. In a preferred method, the optical fiber is coated with a plastic buffer or pliant metal jacket.