Electrically tunable optical fibre polished coupler

Optical fibre polished couplers are widely used primarily because at their unique tunability and very low insertion losses, especially in sensor applications such as ring resonators., gyroscopes and highly accurate interferometric systems. So far, tunability is achieved by mechanically adjusting the core to core separation. This technique suffers form mechanical drifts and in the long term there is the possibility of damaging the polished fibres at the interacting region. The design and operation of an electrically controlled coupler based upon the lap/polished method is described