A Twin-Core and Dual-Hole Fiber Design and Fabrication

We have proposed and demonstrated novel twin-hole and dual-core optical fiber. We used the normal MCVD technology to fabricate a single core fiber preform with a thin cladding. Then, two small holes were drilled in the center and on the side of the pure silica rod, the fabricated single-core fiber preform was inserted into the two holes, and then the combined preform was heated until three parts were fused. Finally, two larger holes were drilled close the center core and twin-core and dual-hole are vertically distributed. In order to retain the shape of air hole, we filled nitrogen gas in the two holes to against the ambient pressure, which made the holes collapse during the fiber drawing. The dual-hole microstructure may be used as micro-containers to inject modulation medium and aside the center core, and to induce accumulated interaction between flow material and evanescent field of the center core, therefore, it can be used as a modulation function fiber to fabricate a very compact in-fiber integrated device.