Broadband power splitters with variable splitting ratios based on AlGaAs-on-insulator platform

For on-chip optical power splitters, the ability to achieve arbitrary splitting-ratios holds potential significance, particularly in applications involving multi-wavelengths with different power ratios, such as χ(3) nonlinear effects. Here, we introduce a 2 × 2 power splitter on an AlGaAs-on-insulator (AlGaAsOI) platform. The proposed device is based on two 2 × 2 50/50 multimode interference (MMI) splitters connected by butterfly shaped waveguides that play the role of a phase shifter. By simply adjusting the length of the phase shifter, these double-MMI couplers can be configured to achieve any desired splitting ratio. The fabricated splitters show splitting ratios varying between 0/100 and 100/0 (at 1550 nm) with a low insertion loss of less than 0.4 dB. Furthermore, the 1-dB bandwidth of the devices is ∼120 nm. The experimental result aligns closely with our simulation, implying the robustness of the design and the fidelity of the fabrication. The demonstrated splitter/combiner will contribute to the high-level integration of AlGaAsOI nonlinear photonics integrated circuits but also open new opportunities for constructing novel-type nonlinear functional devices.