Dual-mode optical 2-to-4 decoder based on cascaded microring resonators.

The optical decoder serves as the logical hub of on-chip photonic integration. Herein, a 2-to-4 decoder consisting of three cascaded silicon waveguide microring resonators (MRRs) is theoretically designed and experimentally demonstrated. Leveraging optical directed logic, this device enables the conversion of 2-bit electrical inputs into 4-bit optical outputs. Via thermal tuning, the fabricated decoder achieves a minimum signal-to-noise ratio of 15.56 dB at an operating wavelength of 1550.75 nm. Furthermore, the proposed dual-mode operation is fully compatible with existing MRR switch arrays, thereby enabling seamless integration into large-scale photonic networks for address decoding, routing control, and logic expansion.