Field matching Y-branch for low loss power splitter

A new approach for lowering the loss at the branching point of a Y-branch power splitter is proposed. By adding a succession of low refractive index regions with selective parameters in the straight waveguide before the branching region, the field matching is improved due to a power pre-splitting effect. The beam propagation method (BPM) is applied for the analysis of the new Y-branch power splitter. This is shown that the loss can be reduced by 50% from a recent work. We also fabricated and tested a 1 × 8 splitter formed by cascaded field matching Y-branches. An improvement of 1 dB from standard Y-branches is achieved while the polarisation dependent loss (PDL) remains lower than 0.25 dB.