Ultra low loss broadband 1 × 2 optical power splitters with various splitting ratios

Abstract

We designed Si-based all-dielectric 1 × 2 TE and TM power splitters with various splitting ratios by combining the use of the inverse design of adjoint and numerical 3D finite-difference time-domain methods. The structure of the designed Si-based power splitters contains two Si waveguide branches on a SiO2 substrate that is compatible with CMOS fabrication technology. The proposed devices exhibit ultra-high transmission efficiency above 98 and 99%, and excess losses below 0.1 and 0.035 dB, for TE and TM splitters, respectively. The merits of these devices include a minor footprint of 2.2 × 2.2 µm2 and a flat-broad operating bandwidth of 200 nm with a center wavelength of λ = 1.55 µm. Also, the other advantage of these optical power splitters is the very short optimization time of 2 h for each device. Because of the aforementioned merits, the optimized devices can be crucial candidates for optical integrated circuits.