Laser-based workstation for the manufacture of fused biconical tapered coupler devices

Fused biconic tapered (FBT) couplers are essential components in today's telecommunications networks where they are used for a number of different applications. The manufacturing process consists of aligning two adjacent fibres from which the buffer has been stripped, and subsequently heating and stretching them, creating an input taper, output taper either side of the fused coupling region. It is the coupling region where energy transfer between cores is possible; this gives the device its main characteristics, and the basic geometry can be used to create a range of devices such as 3 dB splitters, tap couplers, WDMs, etc. Low losses for these devices are achievable if made with reference to the adiabatic approximation. In this paper we report the development of a laser-based rig for the manufacture of couplers in which a CO₂ laser replaces the gas torch typically used as a heat source in modern manufacturing processes. In addition to the use of a laser source, we describe the integration of advanced optical techniques and feedback mechanisms to improve the workstation's reliability and flexibility. These characteristics should be advantageous for efficient manufacture of standard devices and novel devices for niche applications.