Star couplers using fused biconically tapered multimode fibres

We report the fabrication and testing of 4-, 7-and 19-fibre fused biconical taper transmissive star couplers for use with single multimode fibres. Overall insertion losses on six couplers range from ¿1.3 dB to ¿2.6 dB. Losses are nearly independent of N, the number of fibres, but dispersion of the powers in the output fibres increases significantly with N.