Abstract: A multiple optical core fiber and method for manufacturing it. Two or more chemical vapor deposition type preforms are fused with a hydrogen-oxygen torch and then etched in a solution of 50% hydrofluoric and 50% nitric acid. A hollow quartz tube is subjected to internal gas pressure while a hydrogen-oxygen torch is passed along it. This expands and cleans the tube. The chemical vapor deposition preforms are inserted within the expanded tube which is again subjected to the torch to collapse it about the preforms. A nearly solid glass rod with two or more optical waveguide cores is thereby formed. This multiple core preform may then be drawn into a multiple core fiber which can be utilized for the transmission of light pulses.