A twin-core and dual-hole fiber design and fabrication

We have proposed and demonstrated novel twin-hole and dual-core optical fiber. We use the normal MCVD technology to fabricate a single core fiber preform with thin cladding. Then, we drill two small holes in the center and a side position in a pure silica rod and insert the fabricated single core fiber preform into the two holes, heating the combination preform until the three parts fused. Finally, we drill two larger holes close to the center core and twin-hole and dual-core are vertically distributed. In order to contain the shape of air hole, we fill nitrogen gas in the two holes against the ambient pressure, which make the holes collapse during the fiber drawing. The dual-hole may use as micro-containers to inject modulation medium and aside the center core, induced accumulated interaction between flow material and evanescent field of the center core, therefore, it can be used as a modulation function expanded fiber to fabricate a very compact in-fiber integrated device.