Reconfigurable mode-selective TE₀/TE₁ add-drop switch on silicon for multimode photonic networks

We demonstrate a reconfigurable mode-selective TE₀/TE₁ add-drop switch on a silicon-on-insulator platform for multimode photonic networks. By integrating a grating-based backward mode converter, asymmetric bidirectional couplers, and thermo-optic 2 × 2 switches, the proposed device enables direct and reconfigurable access to the TE₀ and TE₁ modes in a multimode bus waveguide without requiring complex intermediate mode processing. Experimental results show that the device successfully achieves selective add-drop operation for both modes. At 1550 nm, all add-drop channels exhibit insertion losses below 1.7 dB and modal crosstalk lower than -17.4 dB. Broadband operation is experimentally demonstrated over the wavelength range of 1510-1600 nm, where the insertion losses remain below 2 dB, and the modal crosstalk is better than -15 dB for all channels. The proposed device provides a compact and scalable solution for flexible multimode photonic networks.