Tee-coupler for single-mode fibres

Abstract
A new concept for an end face tee-coupler with single-mode fibres is described. The outer surfaces of the two fibres are ground and polished on one side and then fixed together. A third fibre is then butt-jointed. The dividing ratio between the two fibres can be chosen arbitrarily. The total loss is about 2 dB. The coupler is polarisation-independent.