Design and fabrication of a metal-based asymmetric and variable Y-branch plastic optical fibre coupler

Abstract

A metal-based asymmetric and variable plastic optical fibre or POF coupler utilising two-optical designs: a Y-branch structure with a novel hollow waveguide taper and an attenuation technique based on lateral displacement of two fibres has been developed. The non-symmetrical coupling ratios are obtained by attenuation due to the lateral displacement of two adjoining fibres. The device has been fabricated on a metal block using high speed CNC machining tool. The fabricated device has an excess loss of 6.3 dB while the coupling ratios are 46.27% and 53.73% when operating as a 3 dB coupler. In the asymmetric coupler mode, the coupling ratio ranges from 14.23% to 85.77% with excess loss varying from 6.3 dB to 8.33 dB. In the variable coupler mode, the device provides coupling ratios of 17.32% to 82.68% and excess loss varying from 6.71 dB to 9.72 dB.