Tunable O-band high-tolerance silicon mode multiplexer based on phase-mismatched asymmetric directional couplers

Small silicon-on-insulator (SOI)-based tunable O-band TE 0 -TE 1 and TE 0 -TE 2 mode multiplexers (MUXs) based on phase-mismatched asymmetric directional couplers (ADCs) are theoretically and experimentally demonstrated. We designed ADCs with an intentionally phase-mismatched coupling region to suppress wavelength dependence and improve fabrication error tolerance. The fabricated O-band TE 0 -TE 2 mode MUX can maintain more than −0.71dB transmission by heating. Moreover, we proposed three-section tapered ADCs (3STADCs) divided into three regions. We theoretically show that the TE 0 -TE 1 and TE 0 -TE 2 mode MUXs based on the 3STADC have more than −0.28dB and −0.36dB transmission within ±10nm waveguide width fabrication error, respectively.