Nanotaper mode converter based on silicon pillar waveguide

A two-dimensional (2D) optimized nanotaper mode converter is presented and analyzed using the finite-difference time-domain (FDTD) method. It can convert the mode size in a silicon pillar waveguide (PWG) from 4 \mum to 1 \mum over a length of 7 \mum and achieve a transmission efficiency of 83.6% at