Demonstration of multiple-wavelength-band photonic integrated circuits using a silicon and silicon nitride 2.5D integration method

Conventional photonic integrated circuits (PICs) are fundamentally limited by single-wavelength-band operation. To transcend this barrier, we introduce a multiple-wavelength-band platform using a 2.5D integration scheme that monolithically combines silicon and silicon nitride waveguides side-by-side on a single chip. This architecture natively supports simultaneous 850 nm and 1,550 nm transmission while eliminating key limitations of 3D integration such as chemical-mechanical polishing and fixed coupling gaps. As a critical demonstration, we realize an all-optical modulator where 850 nm pump light controls a 1,550 nm signal in a silicon microring resonator, achieving a record-high modulation efficiency of −0.023 nm/mW and 93 % depth – surpassing existing schemes. This work establishes a scalable pathway beyond single-band PICs, opening new frontiers in programmable photonics and on-chip signal processing, etc.